MCP server doesn't support charset in the content-type header

[nerzhulart]

Request:

POST http://localhost:64342/message?sessionId=dc88f4aa-5e12-40c6-b355-be080a8cd44c HTTP/1.1
content-type: application/json; charset=utf-8
MCP-Protocol-Version: 2025-06-18
Host: localhost:64342

{"jsonrpc":"2.0","method":"initialize"...

Response:

HTTP/1.1 400
content-length: 74
content-type: text/plain; charset=UTF-8

Invalid message: Unsupported content-type: application/json; charset=utf-8)

But it works with this request:

POST http://localhost:64342/message?sessionId=59a02966-377e-459a-9724-ed3a35a4a62d HTTP/1.1
content-type: application/json
MCP-Protocol-Version: 2025-06-18
Host: localhost:64342

{"jsonrpc":"2.0","method":"initialize"...

Response

HTTP/1.1 202
content-length: 8
content-type: text/plain; charset=UTF-8
...

Issue from https://youtrack.jetbrains.com/issue/IJPL-221890