fix issue where HTTP2 connection could be scavenged but not disposed (#62225)

Co-authored-by: Geoffrey Kizer <geoffrek@windows.microsoft.com>

diff --git a/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/HttpConnectionPool.cs b/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/HttpConnectionPool.cs
index 75b83fb..c51adc8 100644 (file)
--- a/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/HttpConnectionPool.cs
+++ b/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/HttpConnectionPool.cs
@@ -2004,7 +2004,8 @@ namespace System.Net.Http
                 if (freeIndex < list.Count)
                 {
                     // We know the connection at freeIndex is unusable, so dispose of it.
-                    toDispose ??= new List<HttpConnectionBase> { list[freeIndex] };
+                    toDispose ??= new List<HttpConnectionBase>();
+                    toDispose.Add(list[freeIndex]);
 
                     // Find the first item after the one to be removed that should be kept.
                     int current = freeIndex + 1;