Add documentation for TryUpdateParentOfUpdatedNode

src/Analyzers/CSharp/CodeFixes/RemoveUnusedParametersAndValues/CSharpRemoveUnusedValuesCodeFixProvider.cs

@@ -69,7 +69,7 @@ protected override SyntaxNode TryUpdateNameForFlaggedNode(SyntaxNode node, Synta
             }
         }
 
-        protected override SyntaxNode TryUpdateParentOfUpdatedNode(SyntaxNode parent, SyntaxNode newNameNode, SyntaxEditor editor, ISyntaxFactsService syntaxFacts)
+        protected override SyntaxNode TryUpdateParentOfUpdatedNode(SyntaxNode parent, SyntaxNode newNameNode, SyntaxEditor editor, ISyntaxFacts syntaxFacts)
         {
             if (newNameNode.IsKind(SyntaxKind.DiscardDesignation)
                 && parent.IsKind(SyntaxKind.DeclarationPattern, out DeclarationPatternSyntax declarationPattern)

src/Analyzers/Core/CodeFixes/RemoveUnusedParametersAndValues/AbstractRemoveUnusedValuesCodeFixProvider.cs

@@ -103,7 +103,16 @@ internal abstract class AbstractRemoveUnusedValuesCodeFixProvider<TExpressionSyn
             SyntaxEditor editor,
             ISyntaxFactsService syntaxFacts);
 
-        protected virtual SyntaxNode TryUpdateParentOfUpdatedNode(SyntaxNode parent, SyntaxNode newNameNode, SyntaxEditor editor, ISyntaxFactsService syntaxFacts)
+        /// <summary>
+        /// Rewrite the parent of a node which was rewritted by <see cref="TryUpdateNameForFlaggedNode"/>.
+        /// </summary>
+        /// <param name="parent">The original parent of the node rewritten by <see cref="TryUpdateNameForFlaggedNode"/>.</param>
+        /// <param name="newNameNode">The rewritten node produced by <see cref="TryUpdateNameForFlaggedNode"/>.</param>
+        /// <param name="editor">The syntax editor for the code fix.</param>
+        /// <param name="syntaxFacts">The syntax facts for the current language.</param>
+        /// <returns>The replacement node to use in the rewritten syntax tree; otherwise, <see langword="null"/> to only
+        /// rewrite the node originally rewritten by <see cref="TryUpdateNameForFlaggedNode"/>.</returns>
+        protected virtual SyntaxNode TryUpdateParentOfUpdatedNode(SyntaxNode parent, SyntaxNode newNameNode, SyntaxEditor editor, ISyntaxFacts syntaxFacts)
         {
             return null;
         }