Current implementation of HttpServletStreamableServerTransportProvider or HttpServletSseServerTransportProvider needs strict stickyness

Current implementations are holding mcp sessions into a in memory Map https://github.com/modelcontextprotocol/java-sdk/blob/713ee1add0e29d184224aabdf06d024ef30a2754/mcp/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java#L108
This make it mandatory to have strict stickyness "a la" browser" in a replicated/high availability environement which doesn't exist for agent (and we cannot rely on llm agents to implement this)
The feature could be

• first very simple option an option for HttpServletStreamableServerTransportProvider.Builder to have an option to provide the map (then users can use different tools to have some shared Map)
• create an interface to handle those sessions (with minimum operations such add, get. delete)

先從第 108 行附近的記憶體內 session Map 開始檢查 HttpServletStreamableServerTransportProvider.java，接著檢視 HttpServletSseServerTransportProvider 中相同的 session 處理方式。比較由 builder 提供的 Map 方案與 session 管理介面，並定義在沒有嚴格 session 黏著性的複製部署中所需的操作。完成的定義是兩個 servlet transport 都能透過有文件說明的擴充點使用共用的 session 狀態。