Using the curl command:
curl -u 591bf65f50057469f10b5fd9:0cf17f9b03d056ds0e11e48497e506a2 https://backend.tdk.com/api/devicetypes/59147fd79e93s12e61499ffe/me
Spring sets the default content-type to octet-stream when the response is missing that field. All you need to do is to add a message converter to fix this.
octet-stream