spurious validation error when enum declares an abstract method

3.4.0.RELEASE
Build Id: 201310051614

The following enum is valid Groovy code but the IDE complains about an unsupported modifier (is abstract being added to the enum somewhere?):

package test

enum Bad {
	A() {
		@Override
		int foo() {
			1
		}
	}
	abstract int foo()
}

Similar enum in Java works fine:

package test;

enum Fine {
	A() {
		@Override
		int foo() {
			return 1;
		}
	};
	abstract int foo();
}

The command-line Groovy compiler doesn't seem to mind it either. I believe this used to work fine in previous versions of GGTS.