[Feat]: Throw A2AError instead of java.lang exceptions

[wushunhao]

Is your feature request related to a problem? Please describe.

Hi, when I was using the SDK, I noticed that it shows A2AError in many cases.
But sometimes it shows java.lang Exceptions instead.

For instance, in org.a2aproject.sdk.spec.Message, when it checks the parameters like role/parts, it shows java.lang.IllegalArgumentException instead of the org.a2aproject.sdk.spec.InvalidParamsError.

Describe the solution you'd like

I would like the SDK to throw A2AError when possible, so that I can unify the error handling by catching the A2AError only.

Please tell me what you think. Thanks!

Describe alternatives you've considered

No response

Additional context

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[kabir]

I am not sure I understand totally, forgive me if not. Also, I haven't thought through it much, so these are initial thoughts.

If you are talking about user code constructing a Message, I don't think we want to use protocol exceptions there. Similarly to if e.g. a NullPointerException happened for some reason, I don't think we would want to wrap that in some kind of A2AError.

If you mean these java.lang exceptions end up leaking out and being sent over the protocol, then I agree it sounds like a bug.

Do you have a stacktrace so we can confirm what you really mean?