Merge branch 'refs/heads/main' into fix/non-blocking-context

# Conflicts:
#	mcp-test/src/main/java/io/modelcontextprotocol/client/AbstractMcpAsyncClientTests.java
#	mcp/src/main/java/io/modelcontextprotocol/client/McpAsyncClient.java
#	mcp/src/test/java/io/modelcontextprotocol/client/AbstractMcpAsyncClientTests.java

Author: CrazyHZM

mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/server/transport/WebFluxSseServerTransportProvider.java

@@ -188,7 +188,7 @@ public void setSessionFactory(McpServerSession.Factory sessionFactory) {
 	 * errors if any session fails to receive the message
 	 */
 	@Override
-	public Mono<Void> notifyClients(String method, Map<String, Object> params) {
+	public Mono<Void> notifyClients(String method, Object params) {
 		if (sessions.isEmpty()) {
 			logger.debug("No active sessions to broadcast message to");
 			return Mono.empty();
@@ -306,6 +306,11 @@ private Mono<ServerResponse> handleMessage(ServerRequest request) {
 
 		McpServerSession session = sessions.get(request.queryParam("sessionId").get());
 
+		if (session == null) {
+			return ServerResponse.status(HttpStatus.NOT_FOUND)
+				.bodyValue(new McpError("Session not found: " + request.queryParam("sessionId").get()));
+		}
+
 		return request.bodyToMono(String.class).flatMap(body -> {
 			try {
 				McpSchema.JSONRPCMessage message = McpSchema.deserializeJsonRpcMessage(objectMapper, body);