This is an issue similar to #4452.

Bug description
Since we recently added support for the Builder pattern to AssistantMessage, this causes classes like ZhiPuAiAssistantMessage—which inherit from AssistantMessage—to also inherit the builder of AssistantMessage, which is clearly problematic.

Steps to reproduce
Try using ZhiPuAiAssistantMessage.builder().build(), and you'll get an AssistantMessage instead of a ZhiPuAiAssistantMessage.

Expected behavior
ZhiPuAiAssistantMessage.builder().build() should return a ZhiPuAiAssistantMessage.