return new CompactLinkedHashSet<>();
  }

  /**
   * Creates a <i>mutable</i> {@code CompactLinkedHashSet} instance containing the elements of the
   * given collection in the order returned by the collection's iterator.
   *
   * @param collection the elements that the set should contain
   * @return a new {@code CompactLinkedHashSet} containing those elements (minus duplicates)
   */

    assertEquals(expected, CharSource.concat(ImmutableList.of(c1, c2, c3)).read());
    assertEquals(expected, CharSource.concat(c1, c2, c3).read());
    assertEquals(expected, CharSource.concat(ImmutableList.of(c1, c2, c3).iterator()).read());
    assertFalse(CharSource.concat(c1, c2, c3).isEmpty());

    CharSource emptyConcat = CharSource.concat(CharSource.empty(), CharSource.empty());
    assertTrue(emptyConcat.isEmpty());
  }

   * with the entries {@code (3, 5] => "foo", (6, 8) => "bar", (10, 12) => "baz"}.
   *
   * <p>The returned range map supports all optional operations that this range map supports, except
   * for {@code asMapOfRanges().iterator().remove()}.
   *
   * <p>The returned range map will throw an {@link IllegalArgumentException} on an attempt to
   * insert a range not {@linkplain Range#encloses(Range) enclosed} by {@code range}.
   */

            return baseQuery;
        }
        return baseQuery + " sort:" + sortField;
    }

    /**
     * Appends a query string to the query buffer with proper formatting.
     * Handles OR operators and wraps complex queries in parentheses when necessary.
     *
     * @param queryBuf the StringBuilder to append to
     * @param query the query string to append
     */

            throw new NoAvailableChannelException("No healthy channels available");
        }
        
        if (availableChannels.size() == 1) {
            return availableChannels.iterator().next();
        }
        
        switch (strategy) {
            case ROUND_ROBIN:
                return selectRoundRobin(availableChannels);
                
            case LEAST_LOADED:

                }
                throw new ExtractException("PDFBox process cannot finish in " + timeout + " sec.");
            }
            if (!exceptionSet.isEmpty()) {
                throw exceptionSet.iterator().next();
            }
            writer.flush();
            final ExtractData extractData = new ExtractData(writer.toString());
            extractMetadata(document, extractData);
            return extractData;

      if (connections.isEmpty()) cleanupQueue.cancelAll()
      true
    } else {
      scheduleCloser()
      false
    }
  }

  fun evictAll() {
    val i = connections.iterator()
    while (i.hasNext()) {
      val connection = i.next()
      val socketToClose =
        connection.withLock {
          if (connection.calls.isEmpty()) {
            i.remove()

            return new ArrayList<>(this);
        }

        @Override
        public Iterator<V> iterator() {
            if (map != null) {
                return map.values().iterator();
            } else {
                return list.iterator();
            }
        }

        void mergeAll(Collection<V> vs, Remapping<V> remapping) {
            if (map == null) {

    for (int i = 0; i < 3; i++) {
      assertEquals(i + 1, list.get(i).intValue());
    }
    assertEquals(ImmutableList.of(1, 2, 3), ImmutableList.copyOf(list.iterator()));
    assertEquals(ImmutableList.of(1, 2, 3), ImmutableList.copyOf(list.toArray(new Integer[0])));
  }

  @J2ktIncompatible
  @GwtIncompatible // suite
  @AndroidIncompatible // test-suite builders

      serverSocket?.closeQuietly()

      val openClientSocket = openClientSockets.iterator()
      while (openClientSocket.hasNext()) {
        openClientSocket.next().closeQuietly()
        openClientSocket.remove()
      }

      val httpConnection = openConnections.iterator()
      while (httpConnection.hasNext()) {
        httpConnection.next().closeQuietly()
        httpConnection.remove()