Thanks for the addition of the string concatenation refactoring! I really appreciate the effort.

The string concatenation to message template refactor doesn't seem to work when there are newlines or other escaped characters in the text. I think think might be because of L67 of ConvertToMessageTemplateCodeRefactoringProvider.StringConcat.cs

sb.Append(literal.Token.ValueText);

because I think it is then evaluated here:

format = (InterpolatedStringExpressionSyntax)SyntaxFactory.ParseExpression(sb.ToString());

and those are treated as newlines in the code vs the escape value string or something...

e.g. this:

_log4.Debug("RegisterRecorder called with the following parameters: \n FDQN: '" + fqdn + "' \n Guid: '" + id + "' \n Modalities: '" + modalitiesWithCapacity + "' \n URI: '" + uri + "' \n supportedModes: '" + supportedMethods + "' ");

transforms to this:

_log4.Debug("RegisterRecorder called with the following parameters: ");

I'm not really sure how to debug this, but if I can help let me know.