DefaultGroovyMethods class's plus(T[] left, xxxx<T> right) have ambiguous errors

Trying to use the `groovy.transform.etc` for the first time. When I run it, all works well until it gets to `org.codehaus.groovy.runtime.DefaultGroovyMethods.java`

There are a few problems with how the public static <T> T[] plus(T[] left, xxx right) method. Where xxx is T[], Iterable<T> right, or Collection<T> right.

In all of these cases, you just need to change:
return (T[]) plus(...).toArray();
to
return (T[]) plus((Collection<T>)...).toArray();

Problem solved if you follow these instructions.