feat(a2a): Support A2A protocol calling by A2aAgent.

[KomachiSion]

Change-Id: I20d1440c5192294446480da574856119b5aede50

AgentScope-Java Version

1.0.2

Description

Support call remote agent by A2A protocol

Checklist

Please check the following items before code is ready to be reviewed.

• Code has been formatted with mvn spotless:apply
• All tests are passing (mvn test)
• Javadoc comments are complete and follow project conventions
• Related documentation has been updated (e.g. links, examples, etc.)
• Code is ready for review

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[codecov]

Codecov Report

❌ Patch coverage is 89.86083% with 51 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...io/agentscope/core/a2a/agent/utils/LoggerUtil.java	22.58%	17 Missing and 7 partials ⚠️
...core/a2a/agent/event/ClientEventHandlerRouter.java	70.58%	4 Missing and 1 partial ⚠️
...e/core/a2a/agent/event/TaskUpdateEventHandler.java	89.79%	2 Missing and 3 partials ⚠️
...ntscope/core/a2a/agent/message/FilePartParser.java	83.33%	1 Missing and 4 partials ⚠️
...scope/core/a2a/agent/utils/MessageConvertUtil.java	90.56%	2 Missing and 3 partials ⚠️
...ntscope/core/a2a/agent/message/DataPartParser.java	95.12%	0 Missing and 2 partials ⚠️
...scope/core/a2a/agent/message/MessageConstants.java	0.00%	2 Missing ⚠️
...ntscope/core/a2a/agent/message/TextPartParser.java	80.00%	0 Missing and 2 partials ⚠️
...in/java/io/agentscope/core/a2a/agent/A2aAgent.java	99.13%	0 Missing and 1 partial ⚠️

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[Copilot]

Pull request overview

This PR introduces support for the A2A (Agent-to-Agent) protocol in AgentScope-Java, enabling agents to call remote agents using standardized communication. The implementation includes a new A2aAgent class, comprehensive message conversion utilities between AgentScope and A2A formats, and event handlers for managing asynchronous A2A protocol interactions.

• New A2aAgent class that extends AgentBase to support A2A protocol communication
• Bidirectional message converters between AgentScope Msg and A2A Message/Artifact formats
• Support for various content types: text, media (image/audio/video), tool use/results, and thinking blocks
• Event handling infrastructure for processing A2A client events and task updates

Reviewed changes

Copilot reviewed 32 out of 32 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
agentscope-extensions/pom.xml	Adds new a2a-agent module to the extensions
agentscope-dependencies-bom/pom.xml	Adds A2A Java SDK client dependency (version 0.3.2.Final)
agentscope-extensions/.../A2aAgent.java	Core agent implementation with A2A protocol support, lifecycle management, and interrupt handling
agentscope-extensions/.../A2aAgentConfig.java	Configuration record for A2A agent with transport and client config options
agentscope-extensions/.../MessageConvertUtil.java	Utility for bidirectional message conversion between AgentScope and A2A formats
agentscope-extensions/.../LoggerUtil.java	Logging utilities with level checks to avoid unnecessary string formatting
agentscope-extensions/.../message/*.java	Parser implementations for converting between AgentScope ContentBlocks and A2A Parts
agentscope-extensions/.../event/*.java	Event handlers for processing A2A client events, task updates, and messages
agentscope-extensions/.../card/*.java	Agent card resolver implementations for fixed and well-known URLs

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[Copilot]

Pull request overview

Copilot reviewed 34 out of 34 changed files in this pull request and generated 17 comments.

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[Copilot]

Pull request overview

Copilot reviewed 34 out of 34 changed files in this pull request and generated no new comments.

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[AlbumenJ]

Please increase code coverage percentage

[AlbumenJ]

LGTM