Also note this requirement of [oAuth 2.0](https://tools.ietf.org/html/rfc6749#section-3.1.2):
>The endpoint URI MAY include an "application/x-www-form-urlencoded" formatted (per Appendix B) query component ([RFC3986] Section 3.4), which MUST be retained when adding additional query parameters. The endpoint URI MUST NOT include a fragment component.
>To address this shortcoming when generating payloads using this media type, names and values MUST be encoded using the UTF-8 character encoding scheme [RFC3629] first; the resulting octet sequence then needs to be further encoded using the escaping rules defined in [W3C.REC-html401-19991224].