protected String defaultField = Constants.DEFAULT_FIELD;

    /** The analyzer used to analyze query terms */
    protected Analyzer analyzer = new WhitespaceAnalyzer();

    /** Whether to allow leading wildcards in query terms */
    protected boolean allowLeadingWildcard = true;

    /** The default operator to use between query terms */
    protected Operator defaultOperator = Operator.AND;

    /** List of filters to apply to queries */

 * #getUnchecked}, {@link #get(Object, Callable)}, and {@link #getAll} are implemented in terms of
 * {@code get}; {@link #getAllPresent} is implemented in terms of {@code getIfPresent}; {@link
 * #putAll} is implemented in terms of {@link #put}, {@link #invalidateAll(Iterable)} is implemented
 * in terms of {@link #invalidate}. The method {@link #cleanUp} is a no-op. All other methods throw

      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

  protected abstract NavigableSet<E> delegate();

  @Override
  public @Nullable E lower(@ParametricNullness E e) {
    return delegate().lower(e);
  }

  /**
   * A sensible definition of {@link #lower} in terms of the {@code descendingIterator} method of
   * {@link #headSet(Object, boolean)}. If you override {@link #headSet(Object, boolean)}, you may
   * wish to override {@link #lower} to forward to this implementation.
   */

  @Override
  public NavigableSet<E> elementSet() {
    return delegate().elementSet();
  }

  /**
   * A sensible implementation of {@link SortedMultiset#elementSet} in terms of the following
   * methods: {@link SortedMultiset#clear}, {@link SortedMultiset#comparator}, {@link
   * SortedMultiset#contains}, {@link SortedMultiset#containsAll}, {@link SortedMultiset#count},

      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   * #add}, you may wish to override {@link #addAll} to forward to this implementation.
   *
   * @since 7.0
   */
  protected boolean standardAddAll(Collection<? extends E> collection) {
    return Iterators.addAll(this, collection.iterator());
  }

  /**
   * A sensible definition of {@link #remove} in terms of {@link #iterator}, using the iterator's

   * #add}, you may wish to override {@link #addAll} to forward to this implementation.
   *
   * @since 7.0
   */
  protected boolean standardAddAll(Collection<? extends E> collection) {
    return Iterators.addAll(this, collection.iterator());
  }

  /**
   * A sensible definition of {@link #remove} in terms of {@link #iterator}, using the iterator's