And as for backward compatibility, they already did. I love the myth that java never broke backwards compatibility. Bytecode maybe (), they definitely broke syntax compatiblity.
: The various xml parsers and other library thrash really do break backwards bytecode compatiblity.
Proof?
Here's a couple of recent examples the Guava authors have fixed. Fortunately they were in internals and not their public API, so users won't care.
https://code.google.com/p/guava-libraries/source/detail?r=7d... https://code.google.com/p/guava-libraries/source/detail?r=25...
What is meant by "breaking backward compatibility" is when the grammar is altered in a way that makes existing sources no longer compile.