`POST /_matrix/client/v3/rooms/{roomId}/forget` fails to define a request body

**Link to problem area**: https://spec.matrix.org/v1.16/client-server-api/#post_matrixclientv3roomsroomidforget

**Issue**

Presumably the client has to provide an empty JSON object as a body, given the [API standards](https://spec.matrix.org/v1.16/client-server-api/#api-standards)? But that should be clarified in the definition of the API.