fix(server): Fix the logic of the WithStateLess function (#387)

Added a check for the stateLess parameter in the WithStateLess function. Only when stateLess is true, set the sessionIdManager to StatelessSessionIdManager. This modification ensures that the behavior of the WithStateLess function is consistent with expectations and improves the robustness of the code.

Author: dcsunny

server/streamable_http.go

@@ -40,7 +40,9 @@ func WithEndpointPath(endpointPath string) StreamableHTTPOption {
 // to StatelessSessionIdManager.
 func WithStateLess(stateLess bool) StreamableHTTPOption {
 return func(s *StreamableHTTPServer) {
-s.sessionIdManager = &StatelessSessionIdManager{}
+if stateLess {
+s.sessionIdManager = &StatelessSessionIdManager{}
+}
 }
 }