code: private SerializerWrapper getSerializerWrapper(Class cls) {
      SerializerWrapper w = serializers.get(cls);
      if (w != null) {
        return w;
      } else {
        // Try with interfaces implemented
        for (Class c : cls.getInterfaces()) {
          w = serializers.get(c);
          if (w != null) {
            return w;
          }
        }
      }
      return null;
    }
docs: Returns the serializer and its index associated with <code>cls</code>.
  
  @param cls object clas
  @return serializer wrapper object