Misleading error message when trying to publish events without Content-Type header

[jhorstmann]

{
    "type":"http://httpstatus.es/400",
    "title":"Bad Request",
    "status":400,
    "detail":"Unexpected character % in position 0, expected '['"
}

[raychenon]

There is the same error when the JSON body is malformatted ( misnamed fields, extra ", etc) .
For example, here the first character is "

"[
  {
    "data": {
    // ....
    },
    "data_op": "C",
    "metadata": {
      "eid": "d765de34-09c0-4bbb-8b1e-7160a33a0791",
      "occurred_at": "2018-03-15T17:23:20.311+01:00"
    }
  }
]

[adyach]

@raychenon thank you for contribution! I have added the issue for the next team alignment meeting, I will notify you about the outcome once it is ready.