code: @Override
      public void visitClassContext(ClassContext classContext) {
          try {
              JavaClass cls = classContext.getJavaClass();
              if (isSerializable(cls)) {
                  JavaClass superCls = cls.getSuperClass();
                  if (!isSerializable(superCls) && hasSerializableFields(superCls) && !hasSerializingMethods(cls)) {
                      bugReporter.reportBug(new BugInstance(this, BugType.PIS_POSSIBLE_INCOMPLETE_SERIALIZATION.name(), NORMAL_PRIORITY).addClass(cls));
                  }
              }
          } catch (ClassNotFoundException cnfe) {
              bugReporter.reportMissingClass(cnfe);
          }
      }
docs: implements the visitor to look for classes that are serializable, and are derived from non serializable classes and don't either implement methods in
  Externalizable or Serializable to save parent class fields.
  
  @param classContext
  the context object of the currently parsed class