Merge pull request #37182 from krwq/nullable-xml-3

Nullable: System.Xml, part 3

diff --cc src/libraries/System.Private.Xml/src/System/Xml/Core/QueryOutputWriter.cs
Simple merge

diff --cc src/libraries/System.Private.Xml/src/System/Xml/Core/XmlEventCache.cs
index 857f50f,89e7705..20eba74
--- 1/src/libraries/System.Private.Xml/src/System/Xml/Core/XmlEventCache.cs
--- 2/src/libraries/System.Private.Xml/src/System/Xml/Core/XmlEventCache.cs
+++ b/src/libraries/System.Private.Xml/src/System/Xml/Core/XmlEventCache.cs
@@@ -429,12 -430,12 +430,12 @@@ namespace System.Xm
          /// All other WriteValue methods are implemented by XmlWriter to delegate to WriteValue(object) or WriteValue(string), so
          /// only these two methods need to be implemented.
          /// </summary>
-         public override void WriteValue(object value)
+         public override void WriteValue(object? value)
          {
 -            WriteString(XmlUntypedConverter.Untyped.ToString(value, this.resolver));
 +            WriteString(XmlUntypedConverter.Untyped.ToString(value, this._resolver));
          }
  
-         public override void WriteValue(string value)
+         public override void WriteValue(string? value)
          {
              WriteString(value);
          }

diff --cc src/libraries/System.Private.Xml/src/System/Xml/Core/XmlRawWriter.cs
Simple merge

diff --cc src/libraries/System.Private.Xml/src/System/Xml/Core/XmlTextWriter.cs
Simple merge