This is mostly reference for myself, I don't really have a story to tell you or a lesson you can learn from.
So, without further adieu, here are the methods supported by \Drupal::request()
[0] => __construct [1] => initialize [2] => createFromGlobals [3] => create [4] => setFactory [5] => duplicate [6] => __clone [7] => __toString [8] => overrideGlobals [9] => setTrustedProxies [10] => getTrustedProxies [11] => setTrustedHosts [12] => getTrustedHosts [13] => setTrustedHeaderName [14] => getTrustedHeaderName [15] => normalizeQueryString [16] => enableHttpMethodParameterOverride [17] => getHttpMethodParameterOverride [18] => get [19] => getSession [20] => hasPreviousSession [21] => hasSession [22] => setSession [23] => getClientIps [24] => getClientIp [25] => getScriptName [26] => getPathInfo [27] => getBasePath [28] => getBaseUrl [29] => getScheme [30] => getPort [31] => getUser [32] => getPassword [33] => getUserInfo [34] => getHttpHost [35] => getRequestUri [36] => getSchemeAndHttpHost [37] => getUri [38] => getUriForPath [39] => getRelativeUriForPath [40] => getQueryString [41] => isSecure [42] => getHost [43] => setMethod [44] => getMethod [45] => getRealMethod [46] => getMimeType [47] => getFormat [48] => setFormat [49] => getRequestFormat [50] => setRequestFormat [51] => getContentType [52] => setDefaultLocale [53] => getDefaultLocale [54] => setLocale [55] => getLocale [56] => isMethod [57] => isMethodSafe [58] => getContent [59] => getETags [60] => isNoCache [61] => getPreferredLanguage [62] => getLanguages [63] => getCharsets [64] => getEncodings [65] => getAcceptableContentTypes [66] => isXmlHttpRequest