StringBuilder buf = new StringBuilder();
        Supplier<Object> supplier = () -> "test \"quotes\" and \n newline";

        monitorTarget.append(buf, "specialKey", supplier);
        assertEquals("\"specialKey\":\"test \\\"quotes\\\" and \\n newline\"", buf.toString());
    }

    // Test append method with String containing backslash
    public void test_append_stringWithBackslash() {

            super(f, a);
            defaultField = f;
        }

        /**
         * Overrides the field query creation to handle quoted queries specially.
         * For quoted queries on the default field, creates a phrase query instead of a term query.
         *
         * @param field the field to query
         * @param queryText the query text

  @GuardedBy("monitor")
  private void checkCurrentState(State expected) {
    State actual = state();
    if (actual != expected) {
      if (actual == FAILED) {
        // Handle this specially so that we can include the failureCause, if there is one.
        throw new IllegalStateException(
            "Expected the service " + this + " to be " + expected + ", but the service has FAILED",
            failureCause());

        return appendFileterPath(buf, escape(s));
    }

    /**
     * Escapes special regex characters in a string to create a literal pattern.
     * Handles anchor characters (^ and $) specially to preserve their regex meaning.
     *
     * @param s the string to escape
     * @return an escaped regex pattern, or empty string for comments
     */
    protected String escape(final String s) {

  @GuardedBy("monitor")
  private void checkCurrentState(State expected) {
    State actual = state();
    if (actual != expected) {
      if (actual == FAILED) {
        // Handle this specially so that we can include the failureCause, if there is one.
        throw new IllegalStateException(
            "Expected the service " + this + " to be " + expected + ", but the service has FAILED",
            failureCause());

      // that thread's queue, and thus we cannot be replacing a TaskAndThread object that would
      // otherwise have another task queued on to it. Note the exception to this, cancellation, is
      // specially handled in execute() - execute() calls triggered by cancellation are no-ops, and
      // thus don't count.
      requireNonNull(sequencer).latestTaskQueue = executingTaskQueue;
      sequencer = null;
      try {

   *
   * @return Is the domain name syntactically valid?
   */
  private static boolean validateSyntax(List<String> parts) {
    int lastIndex = parts.size() - 1;

    // Validate the last part specially, as it has different syntax rules.

    if (!validatePart(parts.get(lastIndex), true)) {
      return false;
    }

    for (int i = 0; i < lastIndex; i++) {
      String part = parts.get(i);