code: protected final StringBuilder newHeaderValueBuffer() {
          final StringBuilder buf = new StringBuilder(40);
          if (noCache) {
              buf.append(", no-cache");
          }
          if (noStore) {
              buf.append(", no-store");
          }
          if (noTransform) {
              buf.append(", no-transform");
          }
          if (maxAgeSeconds >= 0) {
              buf.append(", max-age=").append(maxAgeSeconds);
          }
          return buf;
      }
docs: Returns a new {@link StringBuilder} with the common directives appended.
  Note that the first two characters ({@code ", "} must be stripped.