Section 6.11 "Registering an Application" is unclear about what Content-Type header must be for various scenarios

While implementing the code for Section 6.11 I noticed that there are a couple of scenarios in which the spec is unclear about the expected Content-Type of the POST request. The more minor of these is the case in which the Consumer POSTs a JSON object that contains the URI of the PDP or DP. Since the request is JSON, an implementer can infer that the Content-Type should be "application/json", but the spec should really be clear about this just to avoid any misunderstandings.

The second, and more serious, case is when the Consumer directly POSTs the contents of a DP in the request body.

This is important because, as defined in the spec, Content-Type is the only information an implementation has to figure out which of the four different methods a Consumer is attempting to use when they POST to the Platform resource.