TCP connections remain in CLOSE_WAIT state after client disconnection in SSE mode

[hty690]

Bug description
When clients terminate SSE connections with the Java MCP server, the underlying TCP connections remain in CLOSE_WAIT state, while the client side stays in FIN_WAIT_2. This can lead to resource leaks, especially in scenarios where clients cannot properly send RST signals (e.g., when using customized user-space network stacks).

Environment
java version: 17
sdk version: 0.10.0
spring-ai.version: 1.0.0

Steps to reproduce

1. setup a plain spring-ai mcp server, listen on localhost:8888/sse
2. use inspector to call 127.0.0.1:8888/sse
3. use inspector to list tool/call tools/...
4. disconnect the connection and use netstat -anp|grep 8888

Expected behavior
All TCP connections should be closed properly.

[gemo12123]

Perhaps you can try manually executing McpServerTransportProvider#notifyClients(McpSchema.METHOD_PING, null) on a scheduled basis.