return !isEmpty(collection);
    }

    /**
     * {@link Map}が{@literal null}または要素が無い場合は{@literal true}を返します。
     *
     * @param map
     *            マップ
     * @return マップが{@literal null}または要素が無い場合は{@literal true}
     */
    public static boolean isEmpty(final Map<?, ?> map) {
        return map == null || map.isEmpty();
    }

    /**

    TreeSet<Derived> set = Sets.newTreeSet();
    assertTrue(set.isEmpty());
    set.add(new Derived("foo"));
    set.add(new Derived("bar"));
    assertThat(set).containsExactly(new Derived("bar"), new Derived("foo")).inOrder();
  }

  public void testNewTreeSetEmptyNonGeneric() {
    TreeSet<LegacyComparable> set = Sets.newTreeSet();
    assertTrue(set.isEmpty());
    set.add(new LegacyComparable("foo"));

    // ----------------------------------------------------------------------

    private void addPath(List<String> paths, String path) {
        if (path != null) {
            path = path.trim();
            if (!path.isEmpty()) {
                File file = new File(path);
                if (file.isAbsolute()) {
                    path = file.getAbsolutePath();
                } else if (".".equals(path)) {

  }

  public void testAsMapEmpty() {
    Set<String> strings = ImmutableSet.of();
    Map<String, Integer> map = Maps.asMap(strings, LENGTH_FUNCTION);
    assertThat(map.entrySet()).isEmpty();
    assertTrue(map.isEmpty());
    assertNull(map.get("five"));
  }

  private static class NonNavigableSortedSet extends ForwardingSortedSet<String> {
    private final SortedSet<String> delegate = Sets.newTreeSet();

      return new KeyIterator();
    }

    @Override
    public int size() {
      return MapMakerInternalMap.this.size();
    }

    @Override
    public boolean isEmpty() {
      return MapMakerInternalMap.this.isEmpty();
    }

    @Override
    public boolean contains(Object o) {
      return MapMakerInternalMap.this.containsKey(o);
    }

    @Override

            buf.append(",\"related_contents\":");
            buf.append(escapeJson(relatedContents));
            buf.append(',');
            buf.append("\"data\":[");
            if (!documentItems.isEmpty()) {
                boolean first1 = true;
                for (final Map<String, Object> document : documentItems) {
                    if (!first1) {
                        buf.append(',');

    return keyOrNull(higherEntry(key));
  }

  @Override
  @CheckForNull
  public Entry<K, V> firstEntry() {
    return isEmpty() ? null : entrySet().asList().get(0);
  }

  @Override
  @CheckForNull
  public Entry<K, V> lastEntry() {
    return isEmpty() ? null : entrySet().asList().get(size() - 1);
  }

  /**
   * Guaranteed to throw an exception and leave the map unmodified.
   *

      return new KeyIterator();
    }

    @Override
    public int size() {
      return MapMakerInternalMap.this.size();
    }

    @Override
    public boolean isEmpty() {
      return MapMakerInternalMap.this.isEmpty();
    }

    @Override
    public boolean contains(Object o) {
      return MapMakerInternalMap.this.containsKey(o);
    }

    @Override

    return keyOrNull(higherEntry(key));
  }

  @Override
  @CheckForNull
  public Entry<K, V> firstEntry() {
    return isEmpty() ? null : entrySet().asList().get(0);
  }

  @Override
  @CheckForNull
  public Entry<K, V> lastEntry() {
    return isEmpty() ? null : entrySet().asList().get(size() - 1);
  }

  /**
   * Guaranteed to throw an exception and leave the map unmodified.
   *

                return pe;
            }
            stack.addFirst(it);
        }
        if (found == null) {
            return pe;
        }

        if (stack.isEmpty()) {
            return pe;
        }
        Object stackElement = stack.removeFirst();
        if (!(stackElement.getClass() == PropertyExpression.class)) {
            return pe;
        }