FULL PRODUCT VERSION :
6.x

A DESCRIPTION OF THE PROBLEM :
source compile with javac 5.x but doesn't on javac 6.x

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile the attached code in 5.x and 6.x

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
expected that code will compile
ACTUAL -
does not compile

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Information:Compilation completed with 2 errors and 0 warnings
Information:2 errors
Information:0 warnings
/home/yohan/workspace/project/sotbicom/src/java/Javac6Und5Difference.java
    Error:Error:line (6)non-static variable this cannot be referenced from a static context
    Error:Error:line (6)non-static variable this cannot be referenced from a static context

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class Javac6Und5Difference {}

enum ENUM {
    ENUM_CONST {
        public AbstractClass method() {
            return new AbstractClass() {
                public boolean method() {
                    return true;
                }
            };
        }
    };

    public abstract AbstractClass method();

    //try remove private modifier and see what happens :)
    private abstract class AbstractClass {
        public abstract boolean method();
    }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
place "static" modifier :
private static abstract class

Release Regression From : 5.0u11
The above release value was the last known release where this 
bug was not reproducible. Since then there has been a regression.