Incorrect URI resolution

[abhimoondra]

Bug description
The resolved request url isn't correct for SSE endpoint

Environment
MCP Java SDK Version : 0.10.0
Java : 24

Steps to reproduce
The following function returns a value which is incorrect: https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp/src/main/java/io/modelcontextprotocol/util/Utils.java#L71-L79

So for base url as : http://localhost:5555/sse
and endpoint url as : ?sessionId=f1decbff-7929-40e8-b872-887425beb6eb

The result is : http://localhost:5555/?sessionId=f1decbff-7929-40e8-b872-887425beb6eb

Expected behavior
I expect the result should be http://localhost:5555/sse?sessionId=f1decbff-7929-40e8-b872-887425beb6eb

Minimal Complete Reproducible example

URI base = new URI("http://localhost:5555/sse");
URI relative = new URI("?sessionId=f1decbff-7929-40e8-b872-887425beb6eb");
URI resolved = base.resolve(relative.toString());
System.out.println(resolved);

[denniskawurek]

I created a first draft for this and appreciate any feedback whether this can be followed this way. I know there's work ongoing for the Streamable HTTP support and want to avoid any duplicated work / conflicts in the code.