code: protected boolean isSerializable() {
  
          for (InterfaceType superIntf: _implDecl.getSuperinterfaces()) {
              if (superIntf.toString().equals("java.io.Serializable")) {
                  return true;
              }
          }
  
          // check to see if the superclass is serializable
          return _superClass != null && _superClass.isSerializable();
      }
docs: Does this control impl on one of it superclasses implement java.io.Serializable?
  @return true if this control impl or one of its superclasses implements java.io.Serializable.