'Determine content type of the request body.
Does not do any body introspection, only checks header'

def get_content_type(self):

    if ('Content-Type' not in self.headers):
        return None
    allowed_types = SUPPORTED_CONTENT_TYPES
    content_type = self.content_type
    if (content_type not in allowed_types):
        raise exception.InvalidContentType(content_type=content_type)
    return content_type
