allow to extend transport implementation to provide additional session handling

Author: mswiderski

mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java

@@ -156,7 +156,7 @@ public class HttpServletSseServerTransportProvider extends HttpServlet implement
 	 * @deprecated Use the builder {@link #builder()} instead for better configuration
 	 * options.
 	 */
-	private HttpServletSseServerTransportProvider(McpJsonMapper jsonMapper, String baseUrl, String messageEndpoint,
+	protected HttpServletSseServerTransportProvider(McpJsonMapper jsonMapper, String baseUrl, String messageEndpoint,
 			String sseEndpoint, Duration keepAliveInterval,
 			McpTransportContextExtractor<HttpServletRequest> contextExtractor) {
 

mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStatelessServerTransport.java

@@ -58,7 +58,7 @@ public class HttpServletStatelessServerTransport extends HttpServlet implements
 
 	private volatile boolean isClosing = false;
 
-	private HttpServletStatelessServerTransport(McpJsonMapper jsonMapper, String mcpEndpoint,
+	protected HttpServletStatelessServerTransport(McpJsonMapper jsonMapper, String mcpEndpoint,
 			McpTransportContextExtractor<HttpServletRequest> contextExtractor) {
 		Assert.notNull(jsonMapper, "jsonMapper must not be null");
 		Assert.notNull(mcpEndpoint, "mcpEndpoint must not be null");

mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java

@@ -129,7 +129,7 @@ public class HttpServletStreamableServerTransportProvider extends HttpServlet
 	 * @param contextExtractor The extractor for transport context from the request.
 	 * @throws IllegalArgumentException if any parameter is null
 	 */
-	private HttpServletStreamableServerTransportProvider(McpJsonMapper jsonMapper, String mcpEndpoint,
+	protected HttpServletStreamableServerTransportProvider(McpJsonMapper jsonMapper, String mcpEndpoint,
 			boolean disallowDelete, McpTransportContextExtractor<HttpServletRequest> contextExtractor,
 			Duration keepAliveInterval) {
 		Assert.notNull(jsonMapper, "JsonMapper must not be null");