Spring AI MCP Server: Support WebMvcStatelessTransport Provider

There doesn't appear to be a way to autoconfigure the stateless transport provider in spring-AI as of 1.0.1 or 1.1.0-SNAPSHOT.

proposed type: options - SYNC - SYNC_STATELESS - STDIO - ASYNC - ASYNC_STATELESS

proposed PR 4144

Expected Behavior Given the following configuration, the Stateless Transport should be utilized.

  ai:
    mcp:
      server:
        name: "example-mcp"
        stateless-message-endpoint: /message // <--- proposed
        version: 1.0.0
        type: SYNC_STATELESS /// <-- proposed
        capabilities:
          completion: true
          resource: true
          prompt: true
          tool: true

Current Behavior

There doesn't appear to be a way to configure the Stateless MCP Server out of the box via autoconfiguration.

Context

I discovered that the OpenAI MCP-Client version 1.0.0 is not sending a Session ID in its requests resulting in HTTP Status Code 400 errors. In order to be compatible with other MCP-Server implementations at my org it looks like I need to support the Stateless transport. That transport already exists at WebMvcStatelessServerTransport.java

Sample request payload from OpenAI's MCP-Client:

{
  "jsonrpc": "2.0",
  "method": "initialize",
  "id": 1,
  "params": {
    "protocolVersion": "2025-03-26",
    "capabilities": {},
    "clientInfo": {
      "name": "openai-mcp",
      "version": "1.0.0"
    }
  }
}

Note that sessionId parameter is missing resulting in a 400 status code

{"cause":null,"stackTrace":[{"classLoaderName":null,"moduleName":null,"moduleVersion":null,"methodName":"handleMessage","fileName":"WebMvcSseServerTransportProvider.java","lineNumber":359,"className":"io.modelcontextprotocol.server.transport.WebMvcSseServerTransportProvider","nativeMethod":false}

....


"localizedMessage":"Session ID missing in message endpoint"}