code: public T requestTrailersSanitizer(
              Function<? super HttpHeaders, ? extends HttpHeaders> requestTrailersSanitizer) {
          this.requestTrailersSanitizer = requireNonNull(requestTrailersSanitizer, "requestTrailersSanitizer");
          return self();
      }
docs: Sets the {@link Function} to use to sanitize request trailing headers before logging. If unset,
  will use {@link Function#identity()}.