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

Non-static initialization blocks:

class Foo {
  Integer x;   
  { x = 1; }
}

UPDATE: This is in fact valid Groovy code.