Exception is thrown in SyntaxEditor when adding a delegate declaration to an interface declaration

[bjornhellander]

Version Used:

4.12.0

Steps to Reproduce:

The following code results in an exception being thrown if parent is an interface declaration and newMember is a delegate declaration:

var syntaxEditor = new SyntaxEditor(orgSyntaxRoot, workspace);
syntaxEditor.AddMember(parent, newMember);
var newSyntaxRoot = syntaxEditor.GetChangedRoot(); // Exception here!

Seems to end up here:

roslyn/src/Workspaces/CSharp/Portable/CodeGeneration/CSharpSyntaxGenerator.cs

Line 884 in 3f2b592

throw ExceptionUtilities.UnexpectedValue(member.Kind());

Expected Behavior:
A new syntax root with the new member added to the parent.

Actual Behavior:
InvalidOperationException is thrown.