Valid Java code that is NOT valid Groovy code?

Question

Most Java code is also syntactically valid Groovy code. However, there are a few exceptions which leads me to my question:

Which constructs/features in Java are syn

Answer 1

Multidimensional arrays, where size is not specified.

def x=new Object[5][];  // ERROR: expression expected 

def x=new Object[5][2]; // this works