The object type to be returned by the API can be specified through the Accept header. The possible values are: application/json for JSON returns, text/xml or application/xml for XML returns, and * or */* for default JSON returns.
If the Accept header is not specified, the return will be the same as that specified in the Content-Type. If the Content-Type is also unspecified, the return will be the default JSON.
For the application to authenticate, the return will always be JSON, even if the Accept header is specified.