Issue 3938 Improve MCP SSE URL configuration documentation and examples

[wilocu]

Summary

This PR addresses the confusion around splitting complex MCP SSE URLs into the required url and sse-endpoint properties. The
functionality already worked correctly, but users lacked clear examples and guidance on how to properly configure complex URLs
like http://localhost:3000/mcp-hub/sse/cf9ec4527e3c4a2cbb149a85ea45ab01.

Changes
Enhanced Documentation:

• JavaDoc improvements in McpSseClientProperties.java with comprehensive URL splitting examples
• AsciiDoc documentation in mcp-client-boot-starter-docs.adoc with real-world configuration examples
• URL splitting guidelines table showing how to split various URL patterns
• Troubleshooting section for common 404 errors

Test Coverage:

• Added mcpHubStyleUrlWithTokenPath() test in McpSseClientPropertiesTests.java
• Validates the exact URL pattern from the GitHub issue
• Ensures complex token-based paths work correctly

Better Error Messages:

• Enhanced error handling in SseHttpClientTransportAutoConfiguration.java
• Clear validation messages explaining proper URL splitting
• Examples in error messages for quick debugging

Testing

• 74/74 tests passing across all MCP client modules
• New test validates the exact user scenario from issue How can I split a usable MCP URL into the ​​baseUri​​ and ​​sseEndpoint​​ required by Spring AI's ​​HttpClientSseClientTransport​​? #3938
• All existing functionality preserved - no breaking changes
• Cross-module compatibility (HttpClient + WebFlux transports)

Files Modified

• auto-configurations/mcp/spring-ai-autoconfigure-mcp-client-common/src/main/java/org/springframework/ai/mcp/client/common/auto
  configure/properties/McpSseClientProperties.java
• auto-configurations/mcp/spring-ai-autoconfigure-mcp-client-common/src/test/java/org/springframework/ai/mcp/client/common/auto
  configure/properties/McpSseClientPropertiesTests.java
• auto-configurations/mcp/spring-ai-autoconfigure-mcp-client-httpclient/src/main/java/org/springframework/ai/mcp/client/httpcli
  ent/autoconfigure/SseHttpClientTransportAutoConfiguration.java
• spring-ai-docs/src/main/antora/modules/ROOT/pages/api/mcp/mcp-client-boot-starter-docs.adoc

Signed-off-by: Mattia Pasetto [email protected]

I am still pretty new to contributions, please double check and let me know of any errors.

[ilayaperumalg]

@wilocu Thanks for the PR! Can you apply similar changes to SseWebFluxTransportAutoConfiguration as well?

[ilayaperumalg]

@wilocu Thanks for the PR improving the SSE URL handling and documentation updates. LGTM, rebased and merged as 357190d