Internal Server Error java.lang.AbstractMethodError:

When ever the invoking class has older version of the other package abstract method signature, this error will be thrown. 

How to recover?

- First compile the correct version of abstract class 

- Then compile the invoker's of this abstract class.  

If both are in the same package, compiler should catch. 

Class Hierarchy:

• java.lang.Object
• • java.lang.Throwable
  • • java.lang.Error
    • • java.lang.LinkageError
      • • java.lang.IncompatibleClassChangeError
        • • java.lang.AbstractMethodError