chore: Update Example to print the actual response returned from Agent

[mbroz2]

Description

The current helloworld example only ends up printing Response: io.a2a.spec.SendMessageResponse@63252cf7 when it does System.out.println("Response: " + response.toString());. I expect the actual intent to be to print the response message sent by the Agent which is what this update does.

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  • The current helloworld example READMEs (client and server) seem to need work beyond this minor update. Happy to handle that under another Issue/PR if strategic and helpful.

Fixes #<issue_number_goes_here> 🦕

[gemini-code-assist]

Summary of Changes

Hello @mbroz2, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

I've updated the HelloWorldClient example to correctly parse and display the actual text content returned from the agent. Previously, the example only printed the toString() representation of the SendMessageResponse object, which wasn't very informative. This change makes the example more useful by demonstrating how to extract and show the real message content received from the agent.

Highlights

• Improved Response Handling: The HelloWorldClient example now correctly extracts and prints the text content from the SendMessageResponse object, providing a more meaningful output.
• New Imports: Necessary imports for EventKind, Part, and TextPart were added to facilitate the proper parsing and extraction of message content.

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[gemini-code-assist]

Code Review

The pull request updates the HelloWorld example client to correctly parse and print the text content from the agent's response message, instead of just printing the response object's toString() representation. The implementation is correct, but I've suggested some minor refactoring to simplify the code by using modern Java features like pattern matching for instanceof and removing some redundant checks. This will make the example code cleaner and more idiomatic.

[gemini-code-assist]

The logic for processing the response message can be simplified for better readability and to follow modern Java practices.

• You can use pattern matching for instanceof to avoid the explicit cast. This is already used on line 63.
• The check result.getKind().equals(Message.MESSAGE) is redundant. The Message class constructor ensures the kind is always "message", so instanceof Message is sufficient.
• The null check for responseMessage.getParts() is also redundant. The Message constructor ensures the parts list is not null.
• It's good practice to use the generic type Part<?> instead of the raw type Part in the for-each loop to match the return type of getParts() and avoid compiler warnings.

            if (result instanceof Message responseMessage) {
                StringBuilder textBuilder = new StringBuilder();
                for (Part<?> part : responseMessage.getParts()) {
                    if (part instanceof TextPart textPart) {
                        textBuilder.append(textPart.getText());
                    }
                }
                System.out.println("Response: " + textBuilder.toString());
            }