When attempting to compile the following groovy code I get the compiler error under groovy 1.7.6 and 1.8.3-beta-3. This has to do with defining an interface (or class) with getters and then defining properties (or final members variables) on a subclass using covariant returns. I can work around this issue by explicitly defining the required getter in the subclass which is rather annoying b/c I like groovy getter generation and in our codebase we are running into this a lot. This is also a problem when using "def" types. I would be glad to assist in any way if I can. Thanks.