try fix session potential leak by server sse ping

[taobaorun]

Motivation and Context

Streamable Potential session leaks when Client Fails to Invoke DELETE

Problem:

The current implementation can leak server-side sessions under the following conditions:

a. Session accumulation due to missing DELETE calls

When a client repeatedly establishes new connections but never issues the required DELETE request, the sessions map inside WebMvcStreamableServerTransportProvider grows unbounded.

i. Explicit DELETE is mandatory
Streamable clients must call the DELETE method when they are destroyed to ensure the server cleans up the corresponding session.
b. Client restarts prevent DELETE execution
If the client process (or container) is restarted before it has a chance to send the DELETE, the server retains the now-orphaned session indefinitely, leading to a rapid accumulation of stale entries.

How Has This Been Tested?

Breaking Changes

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context