[Feat]: Add no-arg overload for `getUserInput()` in `RequestContext` to avoid passing null for default delimiter

[CokeLee777]

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

In io.a2a.server.agentexecution.RequestContext (a2a-java-sdk-server-common), the current getUserInput(String delimiter) method uses null as a signal to apply a default delimiter ("\n"). This is an unintuitive API contract that forces callers to pass null explicitly to get default behavior, which is not idiomatic Java.

// Current: caller must pass null to use default delimiter
context.getUserInput(null);

Describe the solution you'd like

Add a no-argument overload that delegates to the existing method with the default delimiter, without changing the existing signature:

public String getUserInput() {
    return getUserInput("\n");
}

This allows callers to write:

context.getUserInput();      // default "\n" delimiter
context.getUserInput(" ");  // custom delimiter

Describe alternatives you've considered

Replacing the existing method entirely with a cleaner signature that removes the null handling — this would be a breaking change and is not preferred.

Additional context

The existing Javadoc already acknowledges the awkwardness with the null example (context.getUserInput(null); // uses "\n"), which suggests this was recognized as non-ideal at the time of writing. Adding the no-arg overload is fully backward-compatible and requires minimal change.

I'd be happy to submit a PR for this if the proposal is accepted.

Code of Conduct

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

[kabir]

@CokeLee777 for simple fixes like these, please feel free to open a PR directly. No need for an issue for everything

[CokeLee777]

Sounds good, thanks! I’ll open a PR directly next time 🙂

[kabir]

Note that there is already a PR for this one ;)