remove unneeded synchronization. It is a racy single-check, but ok in this case
GROOVY-6289 fix single null argument faulty method selection by removing the special case method and instead use the normal way
GROOVY-6048: fix generics for static inner classes and inner interfaces
Refactored thread safety implementation of method createClassName in order to improve its performance
Made classNamesCounter final to be sure it is not accidentally null in a concurrent situation: thanks to Jochen Theodorou for the review and suggestion
GROOVY-6365: avoid additional wrapping of Object[] into Object[]
GROOVY-6469: NumberNumber specialized call site classes always fall back to slow path