code: private boolean isEnum(int stackPos) throws ClassNotFoundException {
          if (stack.getStackDepth() <= stackPos) {
              return false;
          }
  
          OpcodeStack.Item item = stack.getStackItem(stackPos);
          if (!item.getSignature().startsWith(Values.SIG_QUALIFIED_CLASS_PREFIX)) {
              return false;
          }
  
          JavaClass cls = item.getJavaClass();
          if ((cls == null) || !cls.isEnum()) {
              return false;
          }
  
          // If the cls implements any interface, it's possible the collection
          // is based on that interface, so ignore
          return cls.getInterfaces().length == 0;
      }
docs: returns whether the item at the stackPos location on the stack is an enum, and doesn't implement any interfaces
  
  @param stackPos
  the position on the opstack to check
  
  @return whether the class is an enum
  @throws ClassNotFoundException
  if the class can not be loaded