[1] Draft: OAuth 2.0 Form Post Response Mode - draft 03 ( 版) <http://openid.net/specs/oauth-v2-form-post-response-mode-1_0.html>
[2] OpenID Connect 1.0 ( 版) <https://msdn.microsoft.com/en-us/library/azure/dn645541.aspx>
response_mode
[Required] Indicates the encoding of the response. Supported values are fragment (URL fragment) and form_post (HTTP form POST).
[3] Final: OAuth 2.0 Multiple Response Type Encoding Practices ( 版) <http://openid.net/specs/oauth-v2-multiple-response-types-1_0.html>