Port nullability annotations to refs XmlDocument and XmlSerializer (#41474)

* Port nullability annotations to refs XmlDocument and XmlSerializer

* Fix new System.Data.Common nullability related errors

* Switch nullability of parameter in SoapElementAttribute ctor

diff --git a/src/libraries/System.Data.Common/src/System/Data/Common/ObjectStorage.cs b/src/libraries/System.Data.Common/src/System/Data/Common/ObjectStorage.cs
index 80bc06a..6c2c947 100644 (file)
--- a/src/libraries/System.Data.Common/src/System/Data/Common/ObjectStorage.cs
+++ b/src/libraries/System.Data.Common/src/System/Data/Common/ObjectStorage.cs
@@ -341,7 +341,7 @@ namespace System.Data.Common
 
             StringReader strreader = new StringReader(s);
             XmlSerializer deserializerWithOutRootAttribute = ObjectStorage.GetXmlSerializer(type);
-            return (deserializerWithOutRootAttribute.Deserialize(strreader));
+            return (deserializerWithOutRootAttribute.Deserialize(strreader))!;
         }
 
         // Prevent inlining so that reflection calls are not moved to caller that may be in a different assembly that may have a different grant set.

diff --git a/src/libraries/System.Data.Common/src/System/Data/Common/SqlUDTStorage.cs b/src/libraries/System.Data.Common/src/System/Data/Common/SqlUDTStorage.cs
index 2d00cd9..1743d3f 100644 (file)
--- a/src/libraries/System.Data.Common/src/System/Data/Common/SqlUDTStorage.cs
+++ b/src/libraries/System.Data.Common/src/System/Data/Common/SqlUDTStorage.cs
@@ -161,7 +161,7 @@ namespace System.Data.Common
 
             StringReader strreader = new StringReader(s);
             XmlSerializer deserializerWithOutRootAttribute = ObjectStorage.GetXmlSerializer(_dataType);
-            return (deserializerWithOutRootAttribute.Deserialize(strreader));
+            return (deserializerWithOutRootAttribute.Deserialize(strreader))!;
         }
 
         // Prevent inlining so that reflection calls are not moved to caller that may be in a different assembly that may have a different grant set.
@@ -188,7 +188,7 @@ namespace System.Data.Common
             else
             {
                 XmlSerializer deserializerWithRootAttribute = ObjectStorage.GetXmlSerializer(_dataType, xmlAttrib);
-                return (deserializerWithRootAttribute.Deserialize(xmlReader));
+                return (deserializerWithRootAttribute.Deserialize(xmlReader))!;
             }
         }
 

diff --git a/src/libraries/System.Private.Xml/src/System/Xml/Serialization/SoapElementAttribute.cs b/src/libraries/System.Private.Xml/src/System/Xml/Serialization/SoapElementAttribute.cs
index 4fc30e7..5aa2be3 100644 (file)
--- a/src/libraries/System.Private.Xml/src/System/Xml/Serialization/SoapElementAttribute.cs
+++ b/src/libraries/System.Private.Xml/src/System/Xml/Serialization/SoapElementAttribute.cs
@@ -17,7 +17,7 @@ namespace System.Xml.Serialization
         {
         }
 
-        public SoapElementAttribute(string elementName)
+        public SoapElementAttribute(string? elementName)
         {
             _elementName = elementName;
         }

diff --git a/src/libraries/System.Xml.XmlDocument/ref/System.Xml.XmlDocument.csproj b/src/libraries/System.Xml.XmlDocument/ref/System.Xml.XmlDocument.csproj
index fec7d61..1844179 100644 (file)
--- a/src/libraries/System.Xml.XmlDocument/ref/System.Xml.XmlDocument.csproj
+++ b/src/libraries/System.Xml.XmlDocument/ref/System.Xml.XmlDocument.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent)</TargetFrameworks>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="System.Xml.XmlDocument.cs" />

diff --git a/src/libraries/System.Xml.XmlDocument/src/System.Xml.XmlDocument.csproj b/src/libraries/System.Xml.XmlDocument/src/System.Xml.XmlDocument.csproj
index 2700e39..e6d999d 100644 (file)
--- a/src/libraries/System.Xml.XmlDocument/src/System.Xml.XmlDocument.csproj
+++ b/src/libraries/System.Xml.XmlDocument/src/System.Xml.XmlDocument.csproj
@@ -3,6 +3,7 @@
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IsPartialFacadeAssembly>true</IsPartialFacadeAssembly>
     <TargetFrameworks>$(NetCoreAppCurrent)</TargetFrameworks>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="$(LibrariesProjectRoot)System.Private.Xml\src\System.Private.Xml.csproj" />

diff --git a/src/libraries/System.Xml.XmlSerializer/ref/System.Xml.XmlSerializer.cs b/src/libraries/System.Xml.XmlSerializer/ref/System.Xml.XmlSerializer.cs
index ec64194..47b3000 100644 (file)
--- a/src/libraries/System.Xml.XmlSerializer/ref/System.Xml.XmlSerializer.cs
+++ b/src/libraries/System.Xml.XmlSerializer/ref/System.Xml.XmlSerializer.cs
@@ -35,9 +35,9 @@ namespace System.Xml.Serialization
         public CodeIdentifiers() { }
         public CodeIdentifiers(bool caseSensitive) { }
         public bool UseCamelCasing { get { throw null; } set { } }
-        public void Add(string identifier, object value) { }
+        public void Add(string identifier, object? value) { }
         public void AddReserved(string identifier) { }
-        public string AddUnique(string identifier, object value) { throw null; }
+        public string AddUnique(string identifier, object? value) { throw null; }
         public void Clear() { }
         public bool IsInUse(string identifier) { throw null; }
         public string MakeRightCase(string identifier) { throw null; }
@@ -48,7 +48,7 @@ namespace System.Xml.Serialization
     }
     public partial class ImportContext
     {
-        public ImportContext(System.Xml.Serialization.CodeIdentifiers identifiers, bool shareTypes) { }
+        public ImportContext(System.Xml.Serialization.CodeIdentifiers? identifiers, bool shareTypes) { }
         public bool ShareTypes { get { throw null; } }
         public System.Xml.Serialization.CodeIdentifiers TypeIdentifiers { get { throw null; } }
         public System.Collections.Specialized.StringCollection Warnings { get { throw null; } }
@@ -67,35 +67,39 @@ namespace System.Xml.Serialization
     {
         public SoapAttributeAttribute() { }
         public SoapAttributeAttribute(string attributeName) { }
+        [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
         public string AttributeName { get { throw null; } set { } }
+        [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
         public string DataType { get { throw null; } set { } }
-        public string Namespace { get { throw null; } set { } }
+        public string? Namespace { get { throw null; } set { } }
     }
     public partial class SoapAttributeOverrides
     {
         public SoapAttributeOverrides() { }
-        public System.Xml.Serialization.SoapAttributes this[System.Type type] { get { throw null; } }
-        public System.Xml.Serialization.SoapAttributes this[System.Type type, string member] { get { throw null; } }
-        public void Add(System.Type type, string member, System.Xml.Serialization.SoapAttributes attributes) { }
-        public void Add(System.Type type, System.Xml.Serialization.SoapAttributes attributes) { }
+        public System.Xml.Serialization.SoapAttributes? this[System.Type type] { get { throw null; } }
+        public System.Xml.Serialization.SoapAttributes? this[System.Type type, string member] { get { throw null; } }
+        public void Add(System.Type type, string member, System.Xml.Serialization.SoapAttributes? attributes) { }
+        public void Add(System.Type type, System.Xml.Serialization.SoapAttributes? attributes) { }
     }
     public partial class SoapAttributes
     {
         public SoapAttributes() { }
         public SoapAttributes(System.Reflection.ICustomAttributeProvider provider) { }
-        public System.Xml.Serialization.SoapAttributeAttribute SoapAttribute { get { throw null; } set { } }
-        public object SoapDefaultValue { get { throw null; } set { } }
-        public System.Xml.Serialization.SoapElementAttribute SoapElement { get { throw null; } set { } }
-        public System.Xml.Serialization.SoapEnumAttribute SoapEnum { get { throw null; } set { } }
+        public System.Xml.Serialization.SoapAttributeAttribute? SoapAttribute { get { throw null; } set { } }
+        public object? SoapDefaultValue { get { throw null; } set { } }
+        public System.Xml.Serialization.SoapElementAttribute? SoapElement { get { throw null; } set { } }
+        public System.Xml.Serialization.SoapEnumAttribute? SoapEnum { get { throw null; } set { } }
         public bool SoapIgnore { get { throw null; } set { } }
-        public System.Xml.Serialization.SoapTypeAttribute SoapType { get { throw null; } set { } }
+        public System.Xml.Serialization.SoapTypeAttribute? SoapType { get { throw null; } set { } }
     }
     [System.AttributeUsageAttribute(System.AttributeTargets.Field | System.AttributeTargets.Parameter | System.AttributeTargets.Property | System.AttributeTargets.ReturnValue)]
     public partial class SoapElementAttribute : System.Attribute
     {
         public SoapElementAttribute() { }
-        public SoapElementAttribute(string elementName) { }
+        public SoapElementAttribute(string? elementName) { }
+        [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
         public string DataType { get { throw null; } set { } }
+        [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
         public string ElementName { get { throw null; } set { } }
         public bool IsNullable { get { throw null; } set { } }
     }
@@ -104,6 +108,7 @@ namespace System.Xml.Serialization
     {
         public SoapEnumAttribute() { }
         public SoapEnumAttribute(string name) { }
+        [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
         public string Name { get { throw null; } set { } }
     }
     [System.AttributeUsageAttribute(System.AttributeTargets.Field | System.AttributeTargets.Parameter | System.AttributeTargets.Property | System.AttributeTargets.ReturnValue)]
@@ -120,88 +125,93 @@ namespace System.Xml.Serialization
     public partial class SoapReflectionImporter
     {
         public SoapReflectionImporter() { }
-        public SoapReflectionImporter(string defaultNamespace) { }
-        public SoapReflectionImporter(System.Xml.Serialization.SoapAttributeOverrides attributeOverrides) { }
-        public SoapReflectionImporter(System.Xml.Serialization.SoapAttributeOverrides attributeOverrides, string defaultNamespace) { }
-        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string elementName, string ns, System.Xml.Serialization.XmlReflectionMember[] members) { throw null; }
-        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string elementName, string ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement, bool writeAccessors) { throw null; }
-        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string elementName, string ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement, bool writeAccessors, bool validate) { throw null; }
-        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string elementName, string ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement, bool writeAccessors, bool validate, System.Xml.Serialization.XmlMappingAccess access) { throw null; }
+        public SoapReflectionImporter(string? defaultNamespace) { }
+        public SoapReflectionImporter(System.Xml.Serialization.SoapAttributeOverrides? attributeOverrides) { }
+        public SoapReflectionImporter(System.Xml.Serialization.SoapAttributeOverrides? attributeOverrides, string? defaultNamespace) { }
+        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string? elementName, string? ns, System.Xml.Serialization.XmlReflectionMember[] members) { throw null; }
+        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string? elementName, string? ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement, bool writeAccessors) { throw null; }
+        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string? elementName, string? ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement, bool writeAccessors, bool validate) { throw null; }
+        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string? elementName, string? ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement, bool writeAccessors, bool validate, System.Xml.Serialization.XmlMappingAccess access) { throw null; }
         public System.Xml.Serialization.XmlTypeMapping ImportTypeMapping(System.Type type) { throw null; }
-        public System.Xml.Serialization.XmlTypeMapping ImportTypeMapping(System.Type type, string defaultNamespace) { throw null; }
+        public System.Xml.Serialization.XmlTypeMapping ImportTypeMapping(System.Type type, string? defaultNamespace) { throw null; }
         public void IncludeType(System.Type type) { }
         public void IncludeTypes(System.Reflection.ICustomAttributeProvider provider) { }
     }
     public partial class SoapSchemaMember
     {
         public SoapSchemaMember() { }
+        [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
         public string MemberName { get { throw null; } set { } }
-        public System.Xml.XmlQualifiedName MemberType { get { throw null; } set { } }
+        public System.Xml.XmlQualifiedName? MemberType { get { throw null; } set { } }
     }
     [System.AttributeUsageAttribute(System.AttributeTargets.Class | System.AttributeTargets.Enum | System.AttributeTargets.Interface | System.AttributeTargets.Struct)]
     public partial class SoapTypeAttribute : System.Attribute
     {
         public SoapTypeAttribute() { }
-        public SoapTypeAttribute(string typeName) { }
-        public SoapTypeAttribute(string typeName, string ns) { }
+        public SoapTypeAttribute(string? typeName) { }
+        public SoapTypeAttribute(string? typeName, string? ns) { }
         public bool IncludeInSchema { get { throw null; } set { } }
-        public string Namespace { get { throw null; } set { } }
+        public string? Namespace { get { throw null; } set { } }
+        [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
         public string TypeName { get { throw null; } set { } }
     }
     public partial class UnreferencedObjectEventArgs : System.EventArgs
     {
-        public UnreferencedObjectEventArgs(object o, string id) { }
-        public string UnreferencedId { get { throw null; } }
-        public object UnreferencedObject { get { throw null; } }
+        public UnreferencedObjectEventArgs(object? o, string? id) { }
+        public string? UnreferencedId { get { throw null; } }
+        public object? UnreferencedObject { get { throw null; } }
     }
-    public delegate void UnreferencedObjectEventHandler(object sender, System.Xml.Serialization.UnreferencedObjectEventArgs e);
+    public delegate void UnreferencedObjectEventHandler(object? sender, System.Xml.Serialization.UnreferencedObjectEventArgs e);
     public partial class XmlAnyElementAttributes : System.Collections.CollectionBase
     {
         public XmlAnyElementAttributes() { }
-        public System.Xml.Serialization.XmlAnyElementAttribute this[int index] { get { throw null; } set { } }
-        public int Add(System.Xml.Serialization.XmlAnyElementAttribute attribute) { throw null; }
-        public bool Contains(System.Xml.Serialization.XmlAnyElementAttribute attribute) { throw null; }
+        public System.Xml.Serialization.XmlAnyElementAttribute? this[int index] { get { throw null; } set { } }
+        public int Add(System.Xml.Serialization.XmlAnyElementAttribute? attribute) { throw null; }
+        public bool Contains(System.Xml.Serialization.XmlAnyElementAttribute? attribute) { throw null; }
         public void CopyTo(System.Xml.Serialization.XmlAnyElementAttribute[] array, int index) { }
-        public int IndexOf(System.Xml.Serialization.XmlAnyElementAttribute attribute) { throw null; }
-        public void Insert(int index, System.Xml.Serialization.XmlAnyElementAttribute attribute) { }
-        public void Remove(System.Xml.Serialization.XmlAnyElementAttribute attribute) { }
+        public int IndexOf(System.Xml.Serialization.XmlAnyElementAttribute? attribute) { throw null; }
+        public void Insert(int index, System.Xml.Serialization.XmlAnyElementAttribute? attribute) { }
+        public void Remove(System.Xml.Serialization.XmlAnyElementAttribute? attribute) { }
     }
     [System.AttributeUsageAttribute(System.AttributeTargets.Field | System.AttributeTargets.Parameter | System.AttributeTargets.Property | System.AttributeTargets.ReturnValue, AllowMultiple=false)]
     public partial class XmlArrayAttribute : System.Attribute
     {
         public XmlArrayAttribute() { }
-        public XmlArrayAttribute(string elementName) { }
+        public XmlArrayAttribute(string? elementName) { }
+        [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
         public string ElementName { get { throw null; } set { } }
         public System.Xml.Schema.XmlSchemaForm Form { get { throw null; } set { } }
         public bool IsNullable { get { throw null; } set { } }
-        public string Namespace { get { throw null; } set { } }
+        public string? Namespace { get { throw null; } set { } }
         public int Order { get { throw null; } set { } }
     }
     [System.AttributeUsageAttribute(System.AttributeTargets.Field | System.AttributeTargets.Parameter | System.AttributeTargets.Property | System.AttributeTargets.ReturnValue, AllowMultiple=true)]
     public partial class XmlArrayItemAttribute : System.Attribute
     {
         public XmlArrayItemAttribute() { }
-        public XmlArrayItemAttribute(string elementName) { }
-        public XmlArrayItemAttribute(string elementName, System.Type type) { }
-        public XmlArrayItemAttribute(System.Type type) { }
+        public XmlArrayItemAttribute(string? elementName) { }
+        public XmlArrayItemAttribute(string? elementName, System.Type? type) { }
+        public XmlArrayItemAttribute(System.Type? type) { }
+        [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
         public string DataType { get { throw null; } set { } }
+        [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
         public string ElementName { get { throw null; } set { } }
         public System.Xml.Schema.XmlSchemaForm Form { get { throw null; } set { } }
         public bool IsNullable { get { throw null; } set { } }
-        public string Namespace { get { throw null; } set { } }
+        public string? Namespace { get { throw null; } set { } }
         public int NestingLevel { get { throw null; } set { } }
-        public System.Type Type { get { throw null; } set { } }
+        public System.Type? Type { get { throw null; } set { } }
     }
     public partial class XmlArrayItemAttributes : System.Collections.CollectionBase
     {
         public XmlArrayItemAttributes() { }
-        public System.Xml.Serialization.XmlArrayItemAttribute this[int index] { get { throw null; } set { } }
-        public int Add(System.Xml.Serialization.XmlArrayItemAttribute attribute) { throw null; }
-        public bool Contains(System.Xml.Serialization.XmlArrayItemAttribute attribute) { throw null; }
+        public System.Xml.Serialization.XmlArrayItemAttribute? this[int index] { get { throw null; } set { } }
+        public int Add(System.Xml.Serialization.XmlArrayItemAttribute? attribute) { throw null; }
+        public bool Contains(System.Xml.Serialization.XmlArrayItemAttribute? attribute) { throw null; }
         public void CopyTo(System.Xml.Serialization.XmlArrayItemAttribute[] array, int index) { }
-        public int IndexOf(System.Xml.Serialization.XmlArrayItemAttribute attribute) { throw null; }
-        public void Insert(int index, System.Xml.Serialization.XmlArrayItemAttribute attribute) { }
-        public void Remove(System.Xml.Serialization.XmlArrayItemAttribute attribute) { }
+        public int IndexOf(System.Xml.Serialization.XmlArrayItemAttribute? attribute) { throw null; }
+        public void Insert(int index, System.Xml.Serialization.XmlArrayItemAttribute? attribute) { }
+        public void Remove(System.Xml.Serialization.XmlArrayItemAttribute? attribute) { }
     }
     public partial class XmlAttributeEventArgs : System.EventArgs
     {
@@ -210,62 +220,63 @@ namespace System.Xml.Serialization
         public string ExpectedAttributes { get { throw null; } }
         public int LineNumber { get { throw null; } }
         public int LinePosition { get { throw null; } }
-        public object ObjectBeingDeserialized { get { throw null; } }
+        public object? ObjectBeingDeserialized { get { throw null; } }
     }
-    public delegate void XmlAttributeEventHandler(object sender, System.Xml.Serialization.XmlAttributeEventArgs e);
+    public delegate void XmlAttributeEventHandler(object? sender, System.Xml.Serialization.XmlAttributeEventArgs e);
     public partial class XmlAttributeOverrides
     {
         public XmlAttributeOverrides() { }
-        public System.Xml.Serialization.XmlAttributes this[System.Type type] { get { throw null; } }
-        public System.Xml.Serialization.XmlAttributes this[System.Type type, string member] { get { throw null; } }
-        public void Add(System.Type type, string member, System.Xml.Serialization.XmlAttributes attributes) { }
+        public System.Xml.Serialization.XmlAttributes? this[System.Type type] { get { throw null; } }
+        public System.Xml.Serialization.XmlAttributes? this[System.Type type, string member] { get { throw null; } }
+        public void Add(System.Type type, string member, System.Xml.Serialization.XmlAttributes? attributes) { }
         public void Add(System.Type type, System.Xml.Serialization.XmlAttributes attributes) { }
     }
     public partial class XmlAttributes
     {
         public XmlAttributes() { }
         public XmlAttributes(System.Reflection.ICustomAttributeProvider provider) { }
-        public System.Xml.Serialization.XmlAnyAttributeAttribute XmlAnyAttribute { get { throw null; } set { } }
+        public System.Xml.Serialization.XmlAnyAttributeAttribute? XmlAnyAttribute { get { throw null; } set { } }
         public System.Xml.Serialization.XmlAnyElementAttributes XmlAnyElements { get { throw null; } }
-        public System.Xml.Serialization.XmlArrayAttribute XmlArray { get { throw null; } set { } }
+        public System.Xml.Serialization.XmlArrayAttribute? XmlArray { get { throw null; } set { } }
         public System.Xml.Serialization.XmlArrayItemAttributes XmlArrayItems { get { throw null; } }
-        public System.Xml.Serialization.XmlAttributeAttribute XmlAttribute { get { throw null; } set { } }
-        public System.Xml.Serialization.XmlChoiceIdentifierAttribute XmlChoiceIdentifier { get { throw null; } }
-        public object XmlDefaultValue { get { throw null; } set { } }
+        public System.Xml.Serialization.XmlAttributeAttribute? XmlAttribute { get { throw null; } set { } }
+        public System.Xml.Serialization.XmlChoiceIdentifierAttribute? XmlChoiceIdentifier { get { throw null; } }
+        public object? XmlDefaultValue { get { throw null; } set { } }
         public System.Xml.Serialization.XmlElementAttributes XmlElements { get { throw null; } }
-        public System.Xml.Serialization.XmlEnumAttribute XmlEnum { get { throw null; } set { } }
+        public System.Xml.Serialization.XmlEnumAttribute? XmlEnum { get { throw null; } set { } }
         public bool XmlIgnore { get { throw null; } set { } }
         public bool Xmlns { get { throw null; } set { } }
-        public System.Xml.Serialization.XmlRootAttribute XmlRoot { get { throw null; } set { } }
-        public System.Xml.Serialization.XmlTextAttribute XmlText { get { throw null; } set { } }
-        public System.Xml.Serialization.XmlTypeAttribute XmlType { get { throw null; } set { } }
+        public System.Xml.Serialization.XmlRootAttribute? XmlRoot { get { throw null; } set { } }
+        public System.Xml.Serialization.XmlTextAttribute? XmlText { get { throw null; } set { } }
+        public System.Xml.Serialization.XmlTypeAttribute? XmlType { get { throw null; } set { } }
     }
     [System.AttributeUsageAttribute(System.AttributeTargets.Field | System.AttributeTargets.Parameter | System.AttributeTargets.Property | System.AttributeTargets.ReturnValue, AllowMultiple=false)]
     public partial class XmlChoiceIdentifierAttribute : System.Attribute
     {
         public XmlChoiceIdentifierAttribute() { }
-        public XmlChoiceIdentifierAttribute(string name) { }
+        public XmlChoiceIdentifierAttribute(string? name) { }
+        [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
         public string MemberName { get { throw null; } set { } }
     }
     public partial struct XmlDeserializationEvents
     {
         private object _dummy;
         private int _dummyPrimitive;
-        public System.Xml.Serialization.XmlAttributeEventHandler OnUnknownAttribute { get { throw null; } set { } }
-        public System.Xml.Serialization.XmlElementEventHandler OnUnknownElement { get { throw null; } set { } }
-        public System.Xml.Serialization.XmlNodeEventHandler OnUnknownNode { get { throw null; } set { } }
-        public System.Xml.Serialization.UnreferencedObjectEventHandler OnUnreferencedObject { get { throw null; } set { } }
+        public System.Xml.Serialization.XmlAttributeEventHandler? OnUnknownAttribute { get { throw null; } set { } }
+        public System.Xml.Serialization.XmlElementEventHandler? OnUnknownElement { get { throw null; } set { } }
+        public System.Xml.Serialization.XmlNodeEventHandler? OnUnknownNode { get { throw null; } set { } }
+        public System.Xml.Serialization.UnreferencedObjectEventHandler? OnUnreferencedObject { get { throw null; } set { } }
     }
     public partial class XmlElementAttributes : System.Collections.CollectionBase
     {
         public XmlElementAttributes() { }
-        public System.Xml.Serialization.XmlElementAttribute this[int index] { get { throw null; } set { } }
-        public int Add(System.Xml.Serialization.XmlElementAttribute attribute) { throw null; }
-        public bool Contains(System.Xml.Serialization.XmlElementAttribute attribute) { throw null; }
+        public System.Xml.Serialization.XmlElementAttribute? this[int index] { get { throw null; } set { } }
+        public int Add(System.Xml.Serialization.XmlElementAttribute? attribute) { throw null; }
+        public bool Contains(System.Xml.Serialization.XmlElementAttribute? attribute) { throw null; }
         public void CopyTo(System.Xml.Serialization.XmlElementAttribute[] array, int index) { }
-        public int IndexOf(System.Xml.Serialization.XmlElementAttribute attribute) { throw null; }
-        public void Insert(int index, System.Xml.Serialization.XmlElementAttribute attribute) { }
-        public void Remove(System.Xml.Serialization.XmlElementAttribute attribute) { }
+        public int IndexOf(System.Xml.Serialization.XmlElementAttribute? attribute) { throw null; }
+        public void Insert(int index, System.Xml.Serialization.XmlElementAttribute? attribute) { }
+        public void Remove(System.Xml.Serialization.XmlElementAttribute? attribute) { }
     }
     public partial class XmlElementEventArgs : System.EventArgs
     {
@@ -274,22 +285,22 @@ namespace System.Xml.Serialization
         public string ExpectedElements { get { throw null; } }
         public int LineNumber { get { throw null; } }
         public int LinePosition { get { throw null; } }
-        public object ObjectBeingDeserialized { get { throw null; } }
+        public object? ObjectBeingDeserialized { get { throw null; } }
     }
-    public delegate void XmlElementEventHandler(object sender, System.Xml.Serialization.XmlElementEventArgs e);
+    public delegate void XmlElementEventHandler(object? sender, System.Xml.Serialization.XmlElementEventArgs e);
     [System.AttributeUsageAttribute(System.AttributeTargets.Class | System.AttributeTargets.Interface | System.AttributeTargets.Method | System.AttributeTargets.Struct, AllowMultiple=true)]
     public partial class XmlIncludeAttribute : System.Attribute
     {
-        public XmlIncludeAttribute(System.Type type) { }
-        public System.Type Type { get { throw null; } set { } }
+        public XmlIncludeAttribute(System.Type? type) { }
+        public System.Type? Type { get { throw null; } set { } }
     }
     public abstract partial class XmlMapping
     {
         internal XmlMapping() { }
         public string ElementName { get { throw null; } }
-        public string Namespace { get { throw null; } }
+        public string? Namespace { get { throw null; } }
         public string XsdElementName { get { throw null; } }
-        public void SetKey(string key) { }
+        public void SetKey(string? key) { }
     }
     [System.FlagsAttribute]
     public enum XmlMappingAccess
@@ -305,10 +316,10 @@ namespace System.Xml.Serialization
         public bool CheckSpecified { get { throw null; } }
         public string ElementName { get { throw null; } }
         public string MemberName { get { throw null; } }
-        public string Namespace { get { throw null; } }
+        public string? Namespace { get { throw null; } }
         public string TypeFullName { get { throw null; } }
-        public string TypeName { get { throw null; } }
-        public string TypeNamespace { get { throw null; } }
+        public string? TypeName { get { throw null; } }
+        public string? TypeNamespace { get { throw null; } }
         public string XsdElementName { get { throw null; } }
     }
     public partial class XmlMembersMapping : System.Xml.Serialization.XmlMapping
@@ -316,8 +327,8 @@ namespace System.Xml.Serialization
         internal XmlMembersMapping() { }
         public int Count { get { throw null; } }
         public System.Xml.Serialization.XmlMemberMapping this[int index] { get { throw null; } }
-        public string TypeName { get { throw null; } }
-        public string TypeNamespace { get { throw null; } }
+        public string? TypeName { get { throw null; } }
+        public string? TypeNamespace { get { throw null; } }
     }
     public partial class XmlNodeEventArgs : System.EventArgs
     {
@@ -328,24 +339,24 @@ namespace System.Xml.Serialization
         public string Name { get { throw null; } }
         public string NamespaceURI { get { throw null; } }
         public System.Xml.XmlNodeType NodeType { get { throw null; } }
-        public object ObjectBeingDeserialized { get { throw null; } }
-        public string Text { get { throw null; } }
+        public object? ObjectBeingDeserialized { get { throw null; } }
+        public string? Text { get { throw null; } }
     }
-    public delegate void XmlNodeEventHandler(object sender, System.Xml.Serialization.XmlNodeEventArgs e);
+    public delegate void XmlNodeEventHandler(object? sender, System.Xml.Serialization.XmlNodeEventArgs e);
     public partial class XmlReflectionImporter
     {
         public XmlReflectionImporter() { }
-        public XmlReflectionImporter(string defaultNamespace) { }
-        public XmlReflectionImporter(System.Xml.Serialization.XmlAttributeOverrides attributeOverrides) { }
-        public XmlReflectionImporter(System.Xml.Serialization.XmlAttributeOverrides attributeOverrides, string defaultNamespace) { }
-        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string elementName, string ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement) { throw null; }
-        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string elementName, string ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement, bool rpc) { throw null; }
-        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string elementName, string ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement, bool rpc, bool openModel) { throw null; }
-        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string elementName, string ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement, bool rpc, bool openModel, System.Xml.Serialization.XmlMappingAccess access) { throw null; }
+        public XmlReflectionImporter(string? defaultNamespace) { }
+        public XmlReflectionImporter(System.Xml.Serialization.XmlAttributeOverrides? attributeOverrides) { }
+        public XmlReflectionImporter(System.Xml.Serialization.XmlAttributeOverrides? attributeOverrides, string? defaultNamespace) { }
+        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string? elementName, string? ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement) { throw null; }
+        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string? elementName, string? ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement, bool rpc) { throw null; }
+        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string? elementName, string? ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement, bool rpc, bool openModel) { throw null; }
+        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string? elementName, string? ns, System.Xml.Serialization.XmlReflectionMember[] members, bool hasWrapperElement, bool rpc, bool openModel, System.Xml.Serialization.XmlMappingAccess access) { throw null; }
         public System.Xml.Serialization.XmlTypeMapping ImportTypeMapping(System.Type type) { throw null; }
-        public System.Xml.Serialization.XmlTypeMapping ImportTypeMapping(System.Type type, string defaultNamespace) { throw null; }
-        public System.Xml.Serialization.XmlTypeMapping ImportTypeMapping(System.Type type, System.Xml.Serialization.XmlRootAttribute root) { throw null; }
-        public System.Xml.Serialization.XmlTypeMapping ImportTypeMapping(System.Type type, System.Xml.Serialization.XmlRootAttribute root, string defaultNamespace) { throw null; }
+        public System.Xml.Serialization.XmlTypeMapping ImportTypeMapping(System.Type type, string? defaultNamespace) { throw null; }
+        public System.Xml.Serialization.XmlTypeMapping ImportTypeMapping(System.Type type, System.Xml.Serialization.XmlRootAttribute? root) { throw null; }
+        public System.Xml.Serialization.XmlTypeMapping ImportTypeMapping(System.Type type, System.Xml.Serialization.XmlRootAttribute? root, string? defaultNamespace) { throw null; }
         public void IncludeType(System.Type type) { }
         public void IncludeTypes(System.Reflection.ICustomAttributeProvider provider) { }
     }
@@ -354,7 +365,7 @@ namespace System.Xml.Serialization
         public XmlReflectionMember() { }
         public bool IsReturnValue { get { throw null; } set { } }
         public string MemberName { get { throw null; } set { } }
-        public System.Type MemberType { get { throw null; } set { } }
+        public System.Type? MemberType { get { throw null; } set { } }
         public bool OverrideIsNullable { get { throw null; } set { } }
         public System.Xml.Serialization.SoapAttributes SoapAttributes { get { throw null; } set { } }
         public System.Xml.Serialization.XmlAttributes XmlAttributes { get { throw null; } set { } }
@@ -371,27 +382,27 @@ namespace System.Xml.Serialization
     public partial class XmlSchemaExporter
     {
         public XmlSchemaExporter(System.Xml.Serialization.XmlSchemas schemas) { }
-        public string ExportAnyType(string ns) { throw null; }
-        public string ExportAnyType(System.Xml.Serialization.XmlMembersMapping members) { throw null; }
+        public string ExportAnyType(string? ns) { throw null; }
+        public string? ExportAnyType(System.Xml.Serialization.XmlMembersMapping members) { throw null; }
         public void ExportMembersMapping(System.Xml.Serialization.XmlMembersMapping xmlMembersMapping) { }
         public void ExportMembersMapping(System.Xml.Serialization.XmlMembersMapping xmlMembersMapping, bool exportEnclosingType) { }
-        public System.Xml.XmlQualifiedName ExportTypeMapping(System.Xml.Serialization.XmlMembersMapping xmlMembersMapping) { throw null; }
+        public System.Xml.XmlQualifiedName? ExportTypeMapping(System.Xml.Serialization.XmlMembersMapping xmlMembersMapping) { throw null; }
         public void ExportTypeMapping(System.Xml.Serialization.XmlTypeMapping xmlTypeMapping) { }
     }
     public partial class XmlSchemaImporter : System.Xml.Serialization.SchemaImporter
     {
         public XmlSchemaImporter(System.Xml.Serialization.XmlSchemas schemas) { }
-        public XmlSchemaImporter(System.Xml.Serialization.XmlSchemas schemas, System.Xml.Serialization.CodeIdentifiers typeIdentifiers) { }
-        public System.Xml.Serialization.XmlMembersMapping ImportAnyType(System.Xml.XmlQualifiedName typeName, string elementName) { throw null; }
-        public System.Xml.Serialization.XmlTypeMapping ImportDerivedTypeMapping(System.Xml.XmlQualifiedName name, System.Type baseType) { throw null; }
-        public System.Xml.Serialization.XmlTypeMapping ImportDerivedTypeMapping(System.Xml.XmlQualifiedName name, System.Type baseType, bool baseTypeCanBeIndirect) { throw null; }
-        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string name, string ns, System.Xml.Serialization.SoapSchemaMember[] members) { throw null; }
+        public XmlSchemaImporter(System.Xml.Serialization.XmlSchemas schemas, System.Xml.Serialization.CodeIdentifiers? typeIdentifiers) { }
+        public System.Xml.Serialization.XmlMembersMapping? ImportAnyType(System.Xml.XmlQualifiedName typeName, string elementName) { throw null; }
+        public System.Xml.Serialization.XmlTypeMapping ImportDerivedTypeMapping(System.Xml.XmlQualifiedName name, System.Type? baseType) { throw null; }
+        public System.Xml.Serialization.XmlTypeMapping ImportDerivedTypeMapping(System.Xml.XmlQualifiedName name, System.Type? baseType, bool baseTypeCanBeIndirect) { throw null; }
+        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(string name, string? ns, System.Xml.Serialization.SoapSchemaMember[] members) { throw null; }
         public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(System.Xml.XmlQualifiedName name) { throw null; }
         public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(System.Xml.XmlQualifiedName[] names) { throw null; }
-        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(System.Xml.XmlQualifiedName[] names, System.Type baseType, bool baseTypeCanBeIndirect) { throw null; }
+        public System.Xml.Serialization.XmlMembersMapping ImportMembersMapping(System.Xml.XmlQualifiedName[] names, System.Type? baseType, bool baseTypeCanBeIndirect) { throw null; }
         public System.Xml.Serialization.XmlTypeMapping ImportSchemaType(System.Xml.XmlQualifiedName typeName) { throw null; }
-        public System.Xml.Serialization.XmlTypeMapping ImportSchemaType(System.Xml.XmlQualifiedName typeName, System.Type baseType) { throw null; }
-        public System.Xml.Serialization.XmlTypeMapping ImportSchemaType(System.Xml.XmlQualifiedName typeName, System.Type baseType, bool baseTypeCanBeIndirect) { throw null; }
+        public System.Xml.Serialization.XmlTypeMapping ImportSchemaType(System.Xml.XmlQualifiedName typeName, System.Type? baseType) { throw null; }
+        public System.Xml.Serialization.XmlTypeMapping ImportSchemaType(System.Xml.XmlQualifiedName typeName, System.Type? baseType, bool baseTypeCanBeIndirect) { throw null; }
         public System.Xml.Serialization.XmlTypeMapping ImportTypeMapping(System.Xml.XmlQualifiedName name) { throw null; }
     }
     public partial class XmlSchemas : System.Collections.CollectionBase, System.Collections.Generic.IEnumerable<System.Xml.Schema.XmlSchema>, System.Collections.IEnumerable
@@ -399,34 +410,34 @@ namespace System.Xml.Serialization
         public XmlSchemas() { }
         public bool IsCompiled { get { throw null; } }
         public System.Xml.Schema.XmlSchema this[int index] { get { throw null; } set { } }
-        public System.Xml.Schema.XmlSchema this[string ns] { get { throw null; } }
+        public System.Xml.Schema.XmlSchema? this[string? ns] { get { throw null; } }
         public int Add(System.Xml.Schema.XmlSchema schema) { throw null; }
-        public int Add(System.Xml.Schema.XmlSchema schema, System.Uri baseUri) { throw null; }
+        public int Add(System.Xml.Schema.XmlSchema schema, System.Uri? baseUri) { throw null; }
         public void Add(System.Xml.Serialization.XmlSchemas schemas) { }
         public void AddReference(System.Xml.Schema.XmlSchema schema) { }
-        public void Compile(System.Xml.Schema.ValidationEventHandler handler, bool fullCompile) { }
-        public bool Contains(string targetNamespace) { throw null; }
+        public void Compile(System.Xml.Schema.ValidationEventHandler? handler, bool fullCompile) { }
+        public bool Contains(string? targetNamespace) { throw null; }
         public bool Contains(System.Xml.Schema.XmlSchema schema) { throw null; }
         public void CopyTo(System.Xml.Schema.XmlSchema[] array, int index) { }
-        public object Find(System.Xml.XmlQualifiedName name, System.Type type) { throw null; }
-        public System.Collections.IList GetSchemas(string ns) { throw null; }
+        public object? Find(System.Xml.XmlQualifiedName name, System.Type type) { throw null; }
+        public System.Collections.IList GetSchemas(string? ns) { throw null; }
         public int IndexOf(System.Xml.Schema.XmlSchema schema) { throw null; }
         public void Insert(int index, System.Xml.Schema.XmlSchema schema) { }
         public static bool IsDataSet(System.Xml.Schema.XmlSchema schema) { throw null; }
         protected override void OnClear() { }
-        protected override void OnInsert(int index, object value) { }
-        protected override void OnRemove(int index, object value) { }
-        protected override void OnSet(int index, object oldValue, object newValue) { }
+        protected override void OnInsert(int index, object? value) { }
+        protected override void OnRemove(int index, object? value) { }
+        protected override void OnSet(int index, object? oldValue, object? newValue) { }
         public void Remove(System.Xml.Schema.XmlSchema schema) { }
         System.Collections.Generic.IEnumerator<System.Xml.Schema.XmlSchema> System.Collections.Generic.IEnumerable<System.Xml.Schema.XmlSchema>.GetEnumerator() { throw null; }
     }
-    public delegate void XmlSerializationCollectionFixupCallback(object collection, object collectionItems);
+    public delegate void XmlSerializationCollectionFixupCallback(object? collection, object? collectionItems);
     public delegate void XmlSerializationFixupCallback(object fixup);
     public abstract partial class XmlSerializationGeneratedCode
     {
         protected XmlSerializationGeneratedCode() { }
     }
-    public delegate object XmlSerializationReadCallback();
+    public delegate object? XmlSerializationReadCallback();
     public abstract partial class XmlSerializationReader : System.Xml.Serialization.XmlSerializationGeneratedCode
     {
         protected XmlSerializationReader() { }
@@ -435,29 +446,30 @@ namespace System.Xml.Serialization
         protected bool IsReturnValue { get { throw null; } set { } }
         protected System.Xml.XmlReader Reader { get { throw null; } }
         protected int ReaderCount { get { throw null; } }
-        protected void AddFixup(System.Xml.Serialization.XmlSerializationReader.CollectionFixup fixup) { }
-        protected void AddFixup(System.Xml.Serialization.XmlSerializationReader.Fixup fixup) { }
+        protected void AddFixup(System.Xml.Serialization.XmlSerializationReader.CollectionFixup? fixup) { }
+        protected void AddFixup(System.Xml.Serialization.XmlSerializationReader.Fixup? fixup) { }
         protected void AddReadCallback(string name, string ns, System.Type type, System.Xml.Serialization.XmlSerializationReadCallback read) { }
-        protected void AddTarget(string id, object o) { }
+        protected void AddTarget(string? id, object? o) { }
         protected void CheckReaderCount(ref int whileIterations, ref int readerCount) { }
-        protected string CollapseWhitespace(string value) { throw null; }
-        protected System.Exception CreateAbstractTypeException(string name, string ns) { throw null; }
-        protected System.Exception CreateBadDerivationException(string xsdDerived, string nsDerived, string xsdBase, string nsBase, string clrDerived, string clrBase) { throw null; }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("value")]
+        protected string? CollapseWhitespace(string? value) { throw null; }
+        protected System.Exception CreateAbstractTypeException(string name, string? ns) { throw null; }
+        protected System.Exception CreateBadDerivationException(string? xsdDerived, string? nsDerived, string? xsdBase, string? nsBase, string? clrDerived, string? clrBase) { throw null; }
         protected System.Exception CreateCtorHasSecurityException(string typeName) { throw null; }
         protected System.Exception CreateInaccessibleConstructorException(string typeName) { throw null; }
-        protected System.Exception CreateInvalidCastException(System.Type type, object value) { throw null; }
-        protected System.Exception CreateInvalidCastException(System.Type type, object value, string id) { throw null; }
-        protected System.Exception CreateMissingIXmlSerializableType(string name, string ns, string clrType) { throw null; }
+        protected System.Exception CreateInvalidCastException(System.Type type, object? value) { throw null; }
+        protected System.Exception CreateInvalidCastException(System.Type type, object? value, string? id) { throw null; }
+        protected System.Exception CreateMissingIXmlSerializableType(string? name, string? ns, string? clrType) { throw null; }
         protected System.Exception CreateReadOnlyCollectionException(string name) { throw null; }
-        protected System.Exception CreateUnknownConstantException(string value, System.Type enumType) { throw null; }
+        protected System.Exception CreateUnknownConstantException(string? value, System.Type enumType) { throw null; }
         protected System.Exception CreateUnknownNodeException() { throw null; }
         protected System.Exception CreateUnknownTypeException(System.Xml.XmlQualifiedName type) { throw null; }
-        protected System.Array EnsureArrayIndex(System.Array a, int index, System.Type elementType) { throw null; }
+        protected System.Array EnsureArrayIndex(System.Array? a, int index, System.Type elementType) { throw null; }
         protected void FixupArrayRefs(object fixup) { }
         protected int GetArrayLength(string name, string ns) { throw null; }
         protected bool GetNullAttr() { throw null; }
         protected object GetTarget(string id) { throw null; }
-        protected System.Xml.XmlQualifiedName GetXsiType() { throw null; }
+        protected System.Xml.XmlQualifiedName? GetXsiType() { throw null; }
         protected abstract void InitCallbacks();
         protected abstract void InitIDs();
         protected bool IsXmlnsAttribute(string name) { throw null; }
@@ -465,61 +477,69 @@ namespace System.Xml.Serialization
         protected System.Xml.XmlQualifiedName ReadElementQualifiedName() { throw null; }
         protected void ReadEndElement() { }
         protected bool ReadNull() { throw null; }
-        protected System.Xml.XmlQualifiedName ReadNullableQualifiedName() { throw null; }
-        protected string ReadNullableString() { throw null; }
-        protected bool ReadReference(out string fixupReference) { throw null; }
-        protected object ReadReferencedElement() { throw null; }
-        protected object ReadReferencedElement(string name, string ns) { throw null; }
+        protected System.Xml.XmlQualifiedName? ReadNullableQualifiedName() { throw null; }
+        protected string? ReadNullableString() { throw null; }
+        protected bool ReadReference([System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(true)] out string? fixupReference) { throw null; }
+        protected object? ReadReferencedElement() { throw null; }
+        protected object? ReadReferencedElement(string? name, string? ns) { throw null; }
         protected void ReadReferencedElements() { }
-        protected object ReadReferencingElement(string name, string ns, bool elementCanBeType, out string fixupReference) { throw null; }
-        protected object ReadReferencingElement(string name, string ns, out string fixupReference) { throw null; }
-        protected object ReadReferencingElement(out string fixupReference) { throw null; }
+        protected object? ReadReferencingElement(string? name, string? ns, bool elementCanBeType, out string? fixupReference) { throw null; }
+        protected object? ReadReferencingElement(string? name, string? ns, out string? fixupReference) { throw null; }
+        protected object? ReadReferencingElement(out string? fixupReference) { throw null; }
         protected System.Xml.Serialization.IXmlSerializable ReadSerializable(System.Xml.Serialization.IXmlSerializable serializable) { throw null; }
         protected System.Xml.Serialization.IXmlSerializable ReadSerializable(System.Xml.Serialization.IXmlSerializable serializable, bool wrappedAny) { throw null; }
-        protected string ReadString(string value) { throw null; }
-        protected string ReadString(string value, bool trim) { throw null; }
-        protected object ReadTypedNull(System.Xml.XmlQualifiedName type) { throw null; }
-        protected object ReadTypedPrimitive(System.Xml.XmlQualifiedName type) { throw null; }
-        protected System.Xml.XmlDocument ReadXmlDocument(bool wrapped) { throw null; }
-        protected System.Xml.XmlNode ReadXmlNode(bool wrapped) { throw null; }
-        protected void Referenced(object o) { }
-        protected static System.Reflection.Assembly ResolveDynamicAssembly(string assemblyFullName) { throw null; }
-        protected System.Array ShrinkArray(System.Array a, int length, System.Type elementType, bool isNullable) { throw null; }
-        protected byte[] ToByteArrayBase64(bool isNull) { throw null; }
-        protected static byte[] ToByteArrayBase64(string value) { throw null; }
-        protected byte[] ToByteArrayHex(bool isNull) { throw null; }
-        protected static byte[] ToByteArrayHex(string value) { throw null; }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("value")]
+        protected string? ReadString(string? value) { throw null; }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("value")]
+        protected string? ReadString(string? value, bool trim) { throw null; }
+        protected object? ReadTypedNull(System.Xml.XmlQualifiedName type) { throw null; }
+        protected object? ReadTypedPrimitive(System.Xml.XmlQualifiedName type) { throw null; }
+        protected System.Xml.XmlDocument? ReadXmlDocument(bool wrapped) { throw null; }
+        protected System.Xml.XmlNode? ReadXmlNode(bool wrapped) { throw null; }
+        protected void Referenced(object? o) { }
+        protected static System.Reflection.Assembly? ResolveDynamicAssembly(string assemblyFullName) { throw null; }
+        protected System.Array? ShrinkArray(System.Array? a, int length, System.Type elementType, bool isNullable) { throw null; }
+        protected byte[]? ToByteArrayBase64(bool isNull) { throw null; }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("value")]
+        protected static byte[]? ToByteArrayBase64(string? value) { throw null; }
+        protected byte[]? ToByteArrayHex(bool isNull) { throw null; }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("value")]
+        protected static byte[]? ToByteArrayHex(string? value) { throw null; }
         protected static char ToChar(string value) { throw null; }
         protected static System.DateTime ToDate(string value) { throw null; }
         protected static System.DateTime ToDateTime(string value) { throw null; }
         protected static long ToEnum(string value, System.Collections.Hashtable h, string typeName) { throw null; }
         protected static System.DateTime ToTime(string value) { throw null; }
-        protected static string ToXmlName(string value) { throw null; }
-        protected static string ToXmlNCName(string value) { throw null; }
-        protected static string ToXmlNmToken(string value) { throw null; }
-        protected static string ToXmlNmTokens(string value) { throw null; }
-        protected System.Xml.XmlQualifiedName ToXmlQualifiedName(string value) { throw null; }
-        protected void UnknownAttribute(object o, System.Xml.XmlAttribute attr) { }
-        protected void UnknownAttribute(object o, System.Xml.XmlAttribute attr, string qnames) { }
-        protected void UnknownElement(object o, System.Xml.XmlElement elem) { }
-        protected void UnknownElement(object o, System.Xml.XmlElement elem, string qnames) { }
-        protected void UnknownNode(object o) { }
-        protected void UnknownNode(object o, string qnames) { }
-        protected void UnreferencedObject(string id, object o) { }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("value")]
+        protected static string? ToXmlName(string? value) { throw null; }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("value")]
+        protected static string? ToXmlNCName(string? value) { throw null; }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("value")]
+        protected static string? ToXmlNmToken(string? value) { throw null; }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("value")]
+        protected static string? ToXmlNmTokens(string? value) { throw null; }
+        protected System.Xml.XmlQualifiedName ToXmlQualifiedName(string? value) { throw null; }
+        protected void UnknownAttribute(object? o, System.Xml.XmlAttribute attr) { }
+        protected void UnknownAttribute(object? o, System.Xml.XmlAttribute attr, string? qnames) { }
+        protected void UnknownElement(object? o, System.Xml.XmlElement elem) { }
+        protected void UnknownElement(object? o, System.Xml.XmlElement elem, string? qnames) { }
+        protected void UnknownNode(object? o) { }
+        protected void UnknownNode(object? o, string? qnames) { }
+        protected void UnreferencedObject(string? id, object? o) { }
         protected partial class CollectionFixup
         {
-            public CollectionFixup(object collection, System.Xml.Serialization.XmlSerializationCollectionFixupCallback callback, object collectionItems) { }
+            public CollectionFixup(object? collection, System.Xml.Serialization.XmlSerializationCollectionFixupCallback callback, object collectionItems) { }
             public System.Xml.Serialization.XmlSerializationCollectionFixupCallback Callback { get { throw null; } }
-            public object Collection { get { throw null; } }
+            public object? Collection { get { throw null; } }
             public object CollectionItems { get { throw null; } }
         }
         protected partial class Fixup
         {
-            public Fixup(object o, System.Xml.Serialization.XmlSerializationFixupCallback callback, int count) { }
-            public Fixup(object o, System.Xml.Serialization.XmlSerializationFixupCallback callback, string[] ids) { }
+            public Fixup(object? o, System.Xml.Serialization.XmlSerializationFixupCallback callback, int count) { }
+            public Fixup(object? o, System.Xml.Serialization.XmlSerializationFixupCallback callback, string?[]? ids) { }
             public System.Xml.Serialization.XmlSerializationFixupCallback Callback { get { throw null; } }
-            public string[] Ids { get { throw null; } }
-            public object Source { get { throw null; } set { } }
+            public string?[]? Ids { get { throw null; } }
+            public object? Source { get { throw null; } set { } }
         }
     }
     public delegate void XmlSerializationWriteCallback(object o);
@@ -527,9 +547,9 @@ namespace System.Xml.Serialization
     {
         protected XmlSerializationWriter() { }
         protected bool EscapeName { get { throw null; } set { } }
-        protected System.Collections.ArrayList Namespaces { get { throw null; } set { } }
+        protected System.Collections.ArrayList? Namespaces { get { throw null; } set { } }
         protected System.Xml.XmlWriter Writer { get { throw null; } set { } }
-        protected void AddWriteCallback(System.Type type, string typeName, string typeNs, System.Xml.Serialization.XmlSerializationWriteCallback callback) { }
+        protected void AddWriteCallback(System.Type type, string typeName, string? typeNs, System.Xml.Serialization.XmlSerializationWriteCallback callback) { }
         protected System.Exception CreateChoiceIdentifierValueException(string value, string identifier, string name, string ns) { throw null; }
         protected System.Exception CreateInvalidAnyTypeException(object o) { throw null; }
         protected System.Exception CreateInvalidAnyTypeException(System.Type type) { throw null; }
@@ -540,97 +560,102 @@ namespace System.Xml.Serialization
         protected System.Exception CreateUnknownTypeException(object o) { throw null; }
         protected System.Exception CreateUnknownTypeException(System.Type type) { throw null; }
         protected static byte[] FromByteArrayBase64(byte[] value) { throw null; }
-        protected static string FromByteArrayHex(byte[] value) { throw null; }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("value")]
+        protected static string? FromByteArrayHex(byte[]? value) { throw null; }
         protected static string FromChar(char value) { throw null; }
         protected static string FromDate(System.DateTime value) { throw null; }
         protected static string FromDateTime(System.DateTime value) { throw null; }
         protected static string FromEnum(long value, string[] values, long[] ids) { throw null; }
         protected static string FromEnum(long value, string[] values, long[] ids, string typeName) { throw null; }
         protected static string FromTime(System.DateTime value) { throw null; }
-        protected static string FromXmlName(string name) { throw null; }
-        protected static string FromXmlNCName(string ncName) { throw null; }
-        protected static string FromXmlNmToken(string nmToken) { throw null; }
-        protected static string FromXmlNmTokens(string nmTokens) { throw null; }
-        protected string FromXmlQualifiedName(System.Xml.XmlQualifiedName xmlQualifiedName) { throw null; }
-        protected string FromXmlQualifiedName(System.Xml.XmlQualifiedName xmlQualifiedName, bool ignoreEmpty) { throw null; }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("name")]
+        protected static string? FromXmlName(string? name) { throw null; }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("ncName")]
+        protected static string? FromXmlNCName(string? ncName) { throw null; }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("nmToken")]
+        protected static string? FromXmlNmToken(string? nmToken) { throw null; }
+        [return: System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute("nmTokens")]
+        protected static string? FromXmlNmTokens(string? nmTokens) { throw null; }
+        protected string? FromXmlQualifiedName(System.Xml.XmlQualifiedName? xmlQualifiedName) { throw null; }
+        protected string? FromXmlQualifiedName(System.Xml.XmlQualifiedName? xmlQualifiedName, bool ignoreEmpty) { throw null; }
         protected abstract void InitCallbacks();
-        protected static System.Reflection.Assembly ResolveDynamicAssembly(string assemblyFullName) { throw null; }
+        protected static System.Reflection.Assembly? ResolveDynamicAssembly(string assemblyFullName) { throw null; }
         protected void TopLevelElement() { }
-        protected void WriteAttribute(string localName, byte[] value) { }
-        protected void WriteAttribute(string localName, string value) { }
-        protected void WriteAttribute(string localName, string ns, byte[] value) { }
-        protected void WriteAttribute(string localName, string ns, string value) { }
-        protected void WriteAttribute(string prefix, string localName, string ns, string value) { }
-        protected void WriteElementEncoded(System.Xml.XmlNode node, string name, string ns, bool isNullable, bool any) { }
-        protected void WriteElementLiteral(System.Xml.XmlNode node, string name, string ns, bool isNullable, bool any) { }
-        protected void WriteElementQualifiedName(string localName, string ns, System.Xml.XmlQualifiedName value) { }
-        protected void WriteElementQualifiedName(string localName, string ns, System.Xml.XmlQualifiedName value, System.Xml.XmlQualifiedName xsiType) { }
-        protected void WriteElementQualifiedName(string localName, System.Xml.XmlQualifiedName value) { }
-        protected void WriteElementQualifiedName(string localName, System.Xml.XmlQualifiedName value, System.Xml.XmlQualifiedName xsiType) { }
-        protected void WriteElementString(string localName, string value) { }
-        protected void WriteElementString(string localName, string ns, string value) { }
-        protected void WriteElementString(string localName, string ns, string value, System.Xml.XmlQualifiedName xsiType) { }
-        protected void WriteElementString(string localName, string value, System.Xml.XmlQualifiedName xsiType) { }
-        protected void WriteElementStringRaw(string localName, byte[] value) { }
-        protected void WriteElementStringRaw(string localName, byte[] value, System.Xml.XmlQualifiedName xsiType) { }
-        protected void WriteElementStringRaw(string localName, string value) { }
-        protected void WriteElementStringRaw(string localName, string ns, byte[] value) { }
-        protected void WriteElementStringRaw(string localName, string ns, byte[] value, System.Xml.XmlQualifiedName xsiType) { }
-        protected void WriteElementStringRaw(string localName, string ns, string value) { }
-        protected void WriteElementStringRaw(string localName, string ns, string value, System.Xml.XmlQualifiedName xsiType) { }
-        protected void WriteElementStringRaw(string localName, string value, System.Xml.XmlQualifiedName xsiType) { }
-        protected void WriteEmptyTag(string name) { }
-        protected void WriteEmptyTag(string name, string ns) { }
+        protected void WriteAttribute(string localName, byte[]? value) { }
+        protected void WriteAttribute(string localName, string? value) { }
+        protected void WriteAttribute(string localName, string ns, byte[]? value) { }
+        protected void WriteAttribute(string localName, string? ns, string? value) { }
+        protected void WriteAttribute(string? prefix, string localName, string? ns, string? value) { }
+        protected void WriteElementEncoded(System.Xml.XmlNode? node, string name, string? ns, bool isNullable, bool any) { }
+        protected void WriteElementLiteral(System.Xml.XmlNode? node, string name, string? ns, bool isNullable, bool any) { }
+        protected void WriteElementQualifiedName(string localName, string? ns, System.Xml.XmlQualifiedName? value) { }
+        protected void WriteElementQualifiedName(string localName, string? ns, System.Xml.XmlQualifiedName? value, System.Xml.XmlQualifiedName? xsiType) { }
+        protected void WriteElementQualifiedName(string localName, System.Xml.XmlQualifiedName? value) { }
+        protected void WriteElementQualifiedName(string localName, System.Xml.XmlQualifiedName? value, System.Xml.XmlQualifiedName? xsiType) { }
+        protected void WriteElementString(string localName, string? value) { }
+        protected void WriteElementString(string localName, string? ns, string? value) { }
+        protected void WriteElementString(string localName, string? ns, string? value, System.Xml.XmlQualifiedName? xsiType) { }
+        protected void WriteElementString(string localName, string? value, System.Xml.XmlQualifiedName? xsiType) { }
+        protected void WriteElementStringRaw(string localName, byte[]? value) { }
+        protected void WriteElementStringRaw(string localName, byte[]? value, System.Xml.XmlQualifiedName? xsiType) { }
+        protected void WriteElementStringRaw(string localName, string? value) { }
+        protected void WriteElementStringRaw(string localName, string? ns, byte[]? value) { }
+        protected void WriteElementStringRaw(string localName, string? ns, byte[]? value, System.Xml.XmlQualifiedName? xsiType) { }
+        protected void WriteElementStringRaw(string localName, string? ns, string? value) { }
+        protected void WriteElementStringRaw(string localName, string? ns, string? value, System.Xml.XmlQualifiedName? xsiType) { }
+        protected void WriteElementStringRaw(string localName, string? value, System.Xml.XmlQualifiedName? xsiType) { }
+        protected void WriteEmptyTag(string? name) { }
+        protected void WriteEmptyTag(string? name, string? ns) { }
         protected void WriteEndElement() { }
-        protected void WriteEndElement(object o) { }
+        protected void WriteEndElement(object? o) { }
         protected void WriteId(object o) { }
-        protected void WriteNamespaceDeclarations(System.Xml.Serialization.XmlSerializerNamespaces xmlns) { }
-        protected void WriteNullableQualifiedNameEncoded(string name, string ns, System.Xml.XmlQualifiedName value, System.Xml.XmlQualifiedName xsiType) { }
-        protected void WriteNullableQualifiedNameLiteral(string name, string ns, System.Xml.XmlQualifiedName value) { }
-        protected void WriteNullableStringEncoded(string name, string ns, string value, System.Xml.XmlQualifiedName xsiType) { }
-        protected void WriteNullableStringEncodedRaw(string name, string ns, byte[] value, System.Xml.XmlQualifiedName xsiType) { }
-        protected void WriteNullableStringEncodedRaw(string name, string ns, string value, System.Xml.XmlQualifiedName xsiType) { }
-        protected void WriteNullableStringLiteral(string name, string ns, string value) { }
-        protected void WriteNullableStringLiteralRaw(string name, string ns, byte[] value) { }
-        protected void WriteNullableStringLiteralRaw(string name, string ns, string value) { }
-        protected void WriteNullTagEncoded(string name) { }
-        protected void WriteNullTagEncoded(string name, string ns) { }
-        protected void WriteNullTagLiteral(string name) { }
-        protected void WriteNullTagLiteral(string name, string ns) { }
-        protected void WritePotentiallyReferencingElement(string n, string ns, object o) { }
-        protected void WritePotentiallyReferencingElement(string n, string ns, object o, System.Type ambientType) { }
-        protected void WritePotentiallyReferencingElement(string n, string ns, object o, System.Type ambientType, bool suppressReference) { }
-        protected void WritePotentiallyReferencingElement(string n, string ns, object o, System.Type ambientType, bool suppressReference, bool isNullable) { }
+        protected void WriteNamespaceDeclarations(System.Xml.Serialization.XmlSerializerNamespaces? xmlns) { }
+        protected void WriteNullableQualifiedNameEncoded(string name, string? ns, System.Xml.XmlQualifiedName? value, System.Xml.XmlQualifiedName? xsiType) { }
+        protected void WriteNullableQualifiedNameLiteral(string name, string? ns, System.Xml.XmlQualifiedName? value) { }
+        protected void WriteNullableStringEncoded(string name, string? ns, string? value, System.Xml.XmlQualifiedName? xsiType) { }
+        protected void WriteNullableStringEncodedRaw(string name, string? ns, byte[]? value, System.Xml.XmlQualifiedName? xsiType) { }
+        protected void WriteNullableStringEncodedRaw(string name, string? ns, string? value, System.Xml.XmlQualifiedName? xsiType) { }
+        protected void WriteNullableStringLiteral(string name, string? ns, string? value) { }
+        protected void WriteNullableStringLiteralRaw(string name, string? ns, byte[]? value) { }
+        protected void WriteNullableStringLiteralRaw(string name, string? ns, string? value) { }
+        protected void WriteNullTagEncoded(string? name) { }
+        protected void WriteNullTagEncoded(string? name, string? ns) { }
+        protected void WriteNullTagLiteral(string? name) { }
+        protected void WriteNullTagLiteral(string? name, string? ns) { }
+        protected void WritePotentiallyReferencingElement(string? n, string? ns, object? o) { }
+        protected void WritePotentiallyReferencingElement(string? n, string? ns, object? o, System.Type? ambientType) { }
+        protected void WritePotentiallyReferencingElement(string n, string? ns, object? o, System.Type? ambientType, bool suppressReference) { }
+        protected void WritePotentiallyReferencingElement(string? n, string? ns, object? o, System.Type? ambientType, bool suppressReference, bool isNullable) { }
         protected void WriteReferencedElements() { }
-        protected void WriteReferencingElement(string n, string ns, object o) { }
-        protected void WriteReferencingElement(string n, string ns, object o, bool isNullable) { }
-        protected void WriteRpcResult(string name, string ns) { }
-        protected void WriteSerializable(System.Xml.Serialization.IXmlSerializable serializable, string name, string ns, bool isNullable) { }
-        protected void WriteSerializable(System.Xml.Serialization.IXmlSerializable serializable, string name, string ns, bool isNullable, bool wrapped) { }
+        protected void WriteReferencingElement(string n, string? ns, object? o) { }
+        protected void WriteReferencingElement(string n, string? ns, object? o, bool isNullable) { }
+        protected void WriteRpcResult(string name, string? ns) { }
+        protected void WriteSerializable(System.Xml.Serialization.IXmlSerializable? serializable, string name, string ns, bool isNullable) { }
+        protected void WriteSerializable(System.Xml.Serialization.IXmlSerializable? serializable, string name, string? ns, bool isNullable, bool wrapped) { }
         protected void WriteStartDocument() { }
         protected void WriteStartElement(string name) { }
-        protected void WriteStartElement(string name, string ns) { }
-        protected void WriteStartElement(string name, string ns, bool writePrefixed) { }
-        protected void WriteStartElement(string name, string ns, object o) { }
-        protected void WriteStartElement(string name, string ns, object o, bool writePrefixed) { }
-        protected void WriteStartElement(string name, string ns, object o, bool writePrefixed, System.Xml.Serialization.XmlSerializerNamespaces xmlns) { }
-        protected void WriteTypedPrimitive(string name, string ns, object o, bool xsiType) { }
-        protected void WriteValue(byte[] value) { }
-        protected void WriteValue(string value) { }
+        protected void WriteStartElement(string name, string? ns) { }
+        protected void WriteStartElement(string name, string? ns, bool writePrefixed) { }
+        protected void WriteStartElement(string name, string? ns, object? o) { }
+        protected void WriteStartElement(string name, string? ns, object? o, bool writePrefixed) { }
+        protected void WriteStartElement(string name, string? ns, object? o, bool writePrefixed, System.Xml.Serialization.XmlSerializerNamespaces? xmlns) { }
+        protected void WriteTypedPrimitive(string? name, string? ns, object o, bool xsiType) { }
+        protected void WriteValue(byte[]? value) { }
+        protected void WriteValue(string? value) { }
         protected void WriteXmlAttribute(System.Xml.XmlNode node) { }
-        protected void WriteXmlAttribute(System.Xml.XmlNode node, object container) { }
-        protected void WriteXsiType(string name, string ns) { }
+        protected void WriteXmlAttribute(System.Xml.XmlNode node, object? container) { }
+        protected void WriteXsiType(string name, string? ns) { }
     }
     public partial class XmlSerializer
     {
         protected XmlSerializer() { }
         public XmlSerializer(System.Type type) { }
-        public XmlSerializer(System.Type type, string defaultNamespace) { }
-        public XmlSerializer(System.Type type, System.Type[] extraTypes) { }
-        public XmlSerializer(System.Type type, System.Xml.Serialization.XmlAttributeOverrides overrides) { }
-        public XmlSerializer(System.Type type, System.Xml.Serialization.XmlAttributeOverrides overrides, System.Type[] extraTypes, System.Xml.Serialization.XmlRootAttribute root, string defaultNamespace) { }
-        public XmlSerializer(System.Type type, System.Xml.Serialization.XmlAttributeOverrides overrides, System.Type[] extraTypes, System.Xml.Serialization.XmlRootAttribute root, string defaultNamespace, string location) { }
-        public XmlSerializer(System.Type type, System.Xml.Serialization.XmlRootAttribute root) { }
+        public XmlSerializer(System.Type type, string? defaultNamespace) { }
+        public XmlSerializer(System.Type type, System.Type[]? extraTypes) { }
+        public XmlSerializer(System.Type type, System.Xml.Serialization.XmlAttributeOverrides? overrides) { }
+        public XmlSerializer(System.Type type, System.Xml.Serialization.XmlAttributeOverrides? overrides, System.Type[]? extraTypes, System.Xml.Serialization.XmlRootAttribute? root, string? defaultNamespace) { }
+        public XmlSerializer(System.Type type, System.Xml.Serialization.XmlAttributeOverrides? overrides, System.Type[]? extraTypes, System.Xml.Serialization.XmlRootAttribute? root, string? defaultNamespace, string? location) { }
+        public XmlSerializer(System.Type type, System.Xml.Serialization.XmlRootAttribute? root) { }
         public XmlSerializer(System.Xml.Serialization.XmlTypeMapping xmlTypeMapping) { }
         public event System.Xml.Serialization.XmlAttributeEventHandler UnknownAttribute { add { } remove { } }
         public event System.Xml.Serialization.XmlElementEventHandler UnknownElement { add { } remove { } }
@@ -639,47 +664,47 @@ namespace System.Xml.Serialization
         public virtual bool CanDeserialize(System.Xml.XmlReader xmlReader) { throw null; }
         protected virtual System.Xml.Serialization.XmlSerializationReader CreateReader() { throw null; }
         protected virtual System.Xml.Serialization.XmlSerializationWriter CreateWriter() { throw null; }
-        public object Deserialize(System.IO.Stream stream) { throw null; }
-        public object Deserialize(System.IO.TextReader textReader) { throw null; }
+        public object? Deserialize(System.IO.Stream stream) { throw null; }
+        public object? Deserialize(System.IO.TextReader textReader) { throw null; }
         protected virtual object Deserialize(System.Xml.Serialization.XmlSerializationReader reader) { throw null; }
-        public object Deserialize(System.Xml.XmlReader xmlReader) { throw null; }
-        public object Deserialize(System.Xml.XmlReader xmlReader, string encodingStyle) { throw null; }
-        public object Deserialize(System.Xml.XmlReader xmlReader, string encodingStyle, System.Xml.Serialization.XmlDeserializationEvents events) { throw null; }
-        public object Deserialize(System.Xml.XmlReader xmlReader, System.Xml.Serialization.XmlDeserializationEvents events) { throw null; }
-        public static System.Xml.Serialization.XmlSerializer[] FromMappings(System.Xml.Serialization.XmlMapping[] mappings) { throw null; }
-        public static System.Xml.Serialization.XmlSerializer[] FromMappings(System.Xml.Serialization.XmlMapping[] mappings, System.Type type) { throw null; }
-        public static System.Xml.Serialization.XmlSerializer[] FromTypes(System.Type[] types) { throw null; }
+        public object? Deserialize(System.Xml.XmlReader xmlReader) { throw null; }
+        public object? Deserialize(System.Xml.XmlReader xmlReader, string? encodingStyle) { throw null; }
+        public object? Deserialize(System.Xml.XmlReader xmlReader, string? encodingStyle, System.Xml.Serialization.XmlDeserializationEvents events) { throw null; }
+        public object? Deserialize(System.Xml.XmlReader xmlReader, System.Xml.Serialization.XmlDeserializationEvents events) { throw null; }
+        public static System.Xml.Serialization.XmlSerializer[] FromMappings(System.Xml.Serialization.XmlMapping[]? mappings) { throw null; }
+        public static System.Xml.Serialization.XmlSerializer[] FromMappings(System.Xml.Serialization.XmlMapping[]? mappings, System.Type? type) { throw null; }
+        public static System.Xml.Serialization.XmlSerializer[] FromTypes(System.Type[]? types) { throw null; }
         public static string GetXmlSerializerAssemblyName(System.Type type) { throw null; }
-        public static string GetXmlSerializerAssemblyName(System.Type type, string defaultNamespace) { throw null; }
-        public void Serialize(System.IO.Stream stream, object o) { }
-        public void Serialize(System.IO.Stream stream, object o, System.Xml.Serialization.XmlSerializerNamespaces namespaces) { }
-        public void Serialize(System.IO.TextWriter textWriter, object o) { }
-        public void Serialize(System.IO.TextWriter textWriter, object o, System.Xml.Serialization.XmlSerializerNamespaces namespaces) { }
-        protected virtual void Serialize(object o, System.Xml.Serialization.XmlSerializationWriter writer) { }
-        public void Serialize(System.Xml.XmlWriter xmlWriter, object o) { }
-        public void Serialize(System.Xml.XmlWriter xmlWriter, object o, System.Xml.Serialization.XmlSerializerNamespaces namespaces) { }
-        public void Serialize(System.Xml.XmlWriter xmlWriter, object o, System.Xml.Serialization.XmlSerializerNamespaces namespaces, string encodingStyle) { }
-        public void Serialize(System.Xml.XmlWriter xmlWriter, object o, System.Xml.Serialization.XmlSerializerNamespaces namespaces, string encodingStyle, string id) { }
+        public static string GetXmlSerializerAssemblyName(System.Type type, string? defaultNamespace) { throw null; }
+        public void Serialize(System.IO.Stream stream, object? o) { }
+        public void Serialize(System.IO.Stream stream, object? o, System.Xml.Serialization.XmlSerializerNamespaces? namespaces) { }
+        public void Serialize(System.IO.TextWriter textWriter, object? o) { }
+        public void Serialize(System.IO.TextWriter textWriter, object? o, System.Xml.Serialization.XmlSerializerNamespaces? namespaces) { }
+        protected virtual void Serialize(object? o, System.Xml.Serialization.XmlSerializationWriter writer) { }
+        public void Serialize(System.Xml.XmlWriter xmlWriter, object? o) { }
+        public void Serialize(System.Xml.XmlWriter xmlWriter, object? o, System.Xml.Serialization.XmlSerializerNamespaces? namespaces) { }
+        public void Serialize(System.Xml.XmlWriter xmlWriter, object? o, System.Xml.Serialization.XmlSerializerNamespaces? namespaces, string? encodingStyle) { }
+        public void Serialize(System.Xml.XmlWriter xmlWriter, object? o, System.Xml.Serialization.XmlSerializerNamespaces? namespaces, string? encodingStyle, string? id) { }
     }
     [System.AttributeUsageAttribute(System.AttributeTargets.Class | System.AttributeTargets.Enum | System.AttributeTargets.Interface | System.AttributeTargets.Struct, AllowMultiple=false)]
     public sealed partial class XmlSerializerAssemblyAttribute : System.Attribute
     {
         public XmlSerializerAssemblyAttribute() { }
-        public XmlSerializerAssemblyAttribute(string assemblyName) { }
-        public XmlSerializerAssemblyAttribute(string assemblyName, string codeBase) { }
-        public string AssemblyName { get { throw null; } set { } }
-        public string CodeBase { get { throw null; } set { } }
+        public XmlSerializerAssemblyAttribute(string? assemblyName) { }
+        public XmlSerializerAssemblyAttribute(string? assemblyName, string? codeBase) { }
+        public string? AssemblyName { get { throw null; } set { } }
+        public string? CodeBase { get { throw null; } set { } }
     }
     public partial class XmlSerializerFactory
     {
         public XmlSerializerFactory() { }
         public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Type type) { throw null; }
-        public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Type type, string defaultNamespace) { throw null; }
-        public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Type type, System.Type[] extraTypes) { throw null; }
-        public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Type type, System.Xml.Serialization.XmlAttributeOverrides overrides) { throw null; }
-        public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Type type, System.Xml.Serialization.XmlAttributeOverrides overrides, System.Type[] extraTypes, System.Xml.Serialization.XmlRootAttribute root, string defaultNamespace) { throw null; }
-        public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Type type, System.Xml.Serialization.XmlAttributeOverrides overrides, System.Type[] extraTypes, System.Xml.Serialization.XmlRootAttribute root, string defaultNamespace, string location) { throw null; }
-        public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Type type, System.Xml.Serialization.XmlRootAttribute root) { throw null; }
+        public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Type type, string? defaultNamespace) { throw null; }
+        public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Type type, System.Type[]? extraTypes) { throw null; }
+        public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Type type, System.Xml.Serialization.XmlAttributeOverrides? overrides) { throw null; }
+        public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Type type, System.Xml.Serialization.XmlAttributeOverrides? overrides, System.Type[]? extraTypes, System.Xml.Serialization.XmlRootAttribute? root, string? defaultNamespace) { throw null; }
+        public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Type type, System.Xml.Serialization.XmlAttributeOverrides? overrides, System.Type[]? extraTypes, System.Xml.Serialization.XmlRootAttribute? root, string? defaultNamespace, string? location) { throw null; }
+        public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Type type, System.Xml.Serialization.XmlRootAttribute? root) { throw null; }
         public System.Xml.Serialization.XmlSerializer CreateSerializer(System.Xml.Serialization.XmlTypeMapping xmlTypeMapping) { throw null; }
     }
     public abstract partial class XmlSerializerImplementation
@@ -697,20 +722,21 @@ namespace System.Xml.Serialization
     public sealed partial class XmlSerializerVersionAttribute : System.Attribute
     {
         public XmlSerializerVersionAttribute() { }
-        public XmlSerializerVersionAttribute(System.Type type) { }
-        public string Namespace { get { throw null; } set { } }
-        public string ParentAssemblyId { get { throw null; } set { } }
-        public System.Type Type { get { throw null; } set { } }
-        public string Version { get { throw null; } set { } }
+        public XmlSerializerVersionAttribute(System.Type? type) { }
+        public string? Namespace { get { throw null; } set { } }
+        public string? ParentAssemblyId { get { throw null; } set { } }
+        public System.Type? Type { get { throw null; } set { } }
+        public string? Version { get { throw null; } set { } }
     }
     [System.AttributeUsageAttribute(System.AttributeTargets.Class | System.AttributeTargets.Enum | System.AttributeTargets.Interface | System.AttributeTargets.Struct)]
     public partial class XmlTypeAttribute : System.Attribute
     {
         public XmlTypeAttribute() { }
-        public XmlTypeAttribute(string typeName) { }
+        public XmlTypeAttribute(string? typeName) { }
         public bool AnonymousType { get { throw null; } set { } }
         public bool IncludeInSchema { get { throw null; } set { } }
-        public string Namespace { get { throw null; } set { } }
+        public string? Namespace { get { throw null; } set { } }
+        [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
         public string TypeName { get { throw null; } set { } }
     }
     public partial class XmlTypeMapping : System.Xml.Serialization.XmlMapping
@@ -718,7 +744,7 @@ namespace System.Xml.Serialization
         internal XmlTypeMapping() { }
         public string TypeFullName { get { throw null; } }
         public string TypeName { get { throw null; } }
-        public string XsdTypeName { get { throw null; } }
-        public string XsdTypeNamespace { get { throw null; } }
+        public string? XsdTypeName { get { throw null; } }
+        public string? XsdTypeNamespace { get { throw null; } }
     }
 }

diff --git a/src/libraries/System.Xml.XmlSerializer/ref/System.Xml.XmlSerializer.csproj b/src/libraries/System.Xml.XmlSerializer/ref/System.Xml.XmlSerializer.csproj
index 333596c..a626176 100644 (file)
--- a/src/libraries/System.Xml.XmlSerializer/ref/System.Xml.XmlSerializer.csproj
+++ b/src/libraries/System.Xml.XmlSerializer/ref/System.Xml.XmlSerializer.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent)</TargetFrameworks>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="System.Xml.XmlSerializer.cs" />

diff --git a/src/libraries/System.Xml.XmlSerializer/src/System.Xml.XmlSerializer.csproj b/src/libraries/System.Xml.XmlSerializer/src/System.Xml.XmlSerializer.csproj
index 8159a0e..a2a87b2 100644 (file)
--- a/src/libraries/System.Xml.XmlSerializer/src/System.Xml.XmlSerializer.csproj
+++ b/src/libraries/System.Xml.XmlSerializer/src/System.Xml.XmlSerializer.csproj
@@ -2,6 +2,7 @@
   <PropertyGroup>
     <IsPartialFacadeAssembly>true</IsPartialFacadeAssembly>
     <TargetFrameworks>$(NetCoreAppCurrent)</TargetFrameworks>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="$(LibrariesProjectRoot)System.Private.Xml\src\System.Private.Xml.csproj" />