AssistantMessage doesn't support 'name' property

[tiegang7777]

I found that AssistantMessage doesn't contain name property when I want to build a multi-agent system.
This field allows the model to distinguish the name of the assistant, making it easier for building multi-agent systems to share global context.

Expected Behavior
may be we can add a name property to constructor like this:

`public AssistantMessage(String content, String name) {
            xxx
}`

and post it to provider api.

Current Behavior
no property
Context
deepseek has this property, like https://api-docs.deepseek.com/api/create-chat-completion, and so does open ai.