code: public HttpFileServiceBuilder cacheControl(CharSequence cacheControl) {
          requireNonNull(cacheControl, "cacheControl");
          return setHeader(HttpHeaderNames.CACHE_CONTROL, cacheControl);
      }
docs: Sets the {@code "cache-control"} header. This method is a shortcut of:
  <pre>{@code
  builder.setHeader(HttpHeaderNames.CACHE_CONTROL, cacheControl);
  }</pre>