SHOULD Send with 'application/json' content-type in notifications responses

[YifengWong]

typescript-sdk/packages/server/src/server/webStandardStreamableHttp.ts

Line 670 in 6b4d99f

return new Response(null, { status: 202 });

In notifications responses, there is only the status code 202, but without content-type application/json. It would make my java client requests error, because the java client checks EVERY response with application/json content-type

[YifengWong]

Java client codes in io.modelcontextprotocol.client.transport.HttpClientStreamableHttpTransport