return join(partsList);
  }

  /**
   * Returns a string containing the string representation of each argument, using the previously
   * configured separator between each.
   */
  public final String join(
      @Nullable Object first, @Nullable Object second, @Nullable Object... rest) {
    return join(iterable(first, second, rest));
  }

  /**

    if (bits == 32) {
      return Murmur3_32HashFunction.GOOD_FAST_HASH_32;
    }
    if (bits <= 128) {
      return Murmur3_128HashFunction.GOOD_FAST_HASH_128;
    }

    // Otherwise, join together some 128-bit murmur3s
    int hashFunctionsNeeded = (bits + 127) / 128;
    HashFunction[] hashFunctions = new HashFunction[hashFunctionsNeeded];
    hashFunctions[0] = Murmur3_128HashFunction.GOOD_FAST_HASH_128;

   *
   * <ul>
   *   <li>All non-private static methods are checked such that passing null for any parameter
   *       that's not annotated nullable should throw {@link NullPointerException}.
   *   <li>If there is any non-private constructor or non-private static factory method declared by
   *       {@code cls}, all non-private instance methods will be checked too using the instance

    assertThat(Doubles.join(",", EMPTY)).isEmpty();
    assertThat(Doubles.join(",", ARRAY1)).isEqualTo("1.0");
    assertThat(Doubles.join(",", 1.0, 2.0)).isEqualTo("1.0,2.0");
    assertThat(Doubles.join("", 1.0, 2.0, 3.0)).isEqualTo("1.02.03.0");
  }

  public void testJoinNonTrivialDoubles() {
    assertThat(Doubles.join(",", EMPTY)).isEmpty();
    assertThat(Doubles.join(",", 1.2)).isEqualTo("1.2");

                results[index] = thumbnailGenerator.generate(thumbnailId, outputFile);
            });
            threads[i].start();
        }

        for (Thread thread : threads) {
            thread.join();
        }

        for (boolean result : results) {
            assertTrue(result);
        }
    }

    /**
     * Test implementation of ThumbnailGenerator interface
     */

   *
   * <ul>
   *   <li>All non-private static methods are checked such that passing null for any parameter
   *       that's not annotated nullable should throw {@link NullPointerException}.
   *   <li>If there is any non-private constructor or non-private static factory method declared by
   *       {@code cls}, all non-private instance methods will be checked too using the instance

    assertThat(Doubles.join(",", EMPTY)).isEmpty();
    assertThat(Doubles.join(",", ARRAY1)).isEqualTo("1.0");
    assertThat(Doubles.join(",", 1.0, 2.0)).isEqualTo("1.0,2.0");
    assertThat(Doubles.join("", 1.0, 2.0, 3.0)).isEqualTo("1.02.03.0");
  }

  public void testJoinNonTrivialDoubles() {
    assertThat(Doubles.join(",", EMPTY)).isEmpty();
    assertThat(Doubles.join(",", 1.2)).isEqualTo("1.2");

    waiter1.interrupt();

    waiter1.join();
    waiter2.awaitWaiting(); // should still be blocked

    LockSupport.unpark(waiter2); // spurious wakeup
    waiter2.awaitWaiting(); // should eventually re-park

    future.set(null);
    waiter2.join();
  }

  public void testRemoveWaiter_polling() throws Exception {

   * example, {@code join("-", 1, 2, 3)} returns the string {@code "1-2-3"}.
   *
   * @param separator the text that should appear between consecutive values in the resulting string
   *     (but not at the start or end)
   * @param array an array of {@code int} values, possibly empty
   */
  public static String join(String separator, int... array) {
    checkNotNull(separator);

   * For example, {@code join("-", false, true, false)} returns the string {@code
   * "false-true-false"}.
   *
   * @param separator the text that should appear between consecutive values in the resulting string
   *     (but not at the start or end)
   * @param array an array of {@code boolean} values, possibly empty
   */
  public static String join(String separator, boolean... array) {