/** The key of the configuration. e.g. * */
    String API_CORS_ALLOW_ORIGIN = "api.cors.allow.origin";

    /** The key of the configuration. e.g. GET, POST, OPTIONS, DELETE, PUT */
    String API_CORS_ALLOW_METHODS = "api.cors.allow.methods";

    /** The key of the configuration. e.g. 3600 */
    String API_CORS_MAX_AGE = "api.cors.max.age";

of `text/plain` containing JSON data would be accepted and the JSON data would be extracted.

But requests with content type `text/plain` are exempt from [CORS](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS) preflights, for being considered [Simple requests](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS#simple_requests). So, the browser would execute them right away including cookies, and the text content could be a JSON string that would be parsed and accepted by the...