/** The HTTP {@code Content-Length} header field name. */
  public static final String CONTENT_LENGTH = "Content-Length";
  /** The HTTP {@code Content-Type} header field name. */
  public static final String CONTENT_TYPE = "Content-Type";
  /** The HTTP {@code Date} header field name. */
  public static final String DATE = "Date";
  /** The HTTP {@code Pragma} header field name. */