.put("X_WEBKIT_CSP_REPORT_ONLY", "X-WebKit-CSP-Report-Only")
            .buildOrThrow();
    ImmutableSet<String> uppercaseAcronyms =
        ImmutableSet.of(
            "CDN", "CH", "ID", "DNT", "DNS", "DPR", "ECT", "GPC", "HTTP2", "IP", "MD5", "P3P",
            "RTT", "TE", "UA", "UID", "URL", "WWW", "XSS");

    for (Field field : httpHeadersFields()) {
      assertThat(field.get(null))

  public static final String WWW_AUTHENTICATE = "WWW-Authenticate";

  // Common, non-standard HTTP header fields

  /** The HTTP {@code DNT} header field name. */
  public static final String DNT = "DNT";

  /** The HTTP {@code X-Content-Type-Options} header field name. */
  public static final String X_CONTENT_TYPE_OPTIONS = "X-Content-Type-Options";

  /**
   * The HTTP <a