Request body with message should be required in terminate agreement

[kmazurek]

API: Market
Endpoint: POST /agreements/{agreementId}/terminate (on both provider and requestor APIs)

For the above endpoint, only agreementId parameter is marked as required in the API spec. Request body is marked as optional (and is generated as such). However, using this endpoint I found out that the request body is required and must include a message field.

Otherwise, the server returns a 400 with either Json deserialize error: EOF while parsing a value at line 1 column 0 or Json deserialize error: missing field message at line 1 column 2, depending on whether we pass an empty request body or not.