Interface1 declares two methods, MethodA() and MethodB().
 Interface2 declares two methods, MethodA() and MethodC().

 At the start of the sequence, testInterface does not implement either
 Interfacel or Interface2, so the class declaration is just:
 class testInterface extends Object {
   public testInterface() { }
 }

 Extend the declaration to include the interfaces, but do not yet declare the

 interface`s methods:
 class testInterface extends Object implements Interface1, Interface2 {
   public testInterface() { }
 }

 Synchronise the testInterface class. The dialog pops up. Notice in the list
 that MethodA() is (correctly) listed twice, as it is declared in both of the
 interfaces.

 Select "Process All" (to get all the methods in). Under my environment, the
 exception I reported occurs (I just reproduced it while writing this
 message).

 It`s not a fatal error... the IDE is left in a workable state afterwards,
 and the testInterface class is updated correctly to be:
 class testInterface extends Object implements Interface1, Interface2 {
   public testInterface() { }
   void MethodA() { }
   void MethodB() { }
   void MethodC() { }
 }



See attachment for stack trace of exception