@CheckForNull
    public E pollLast() {
      synchronized (mutex) {
        return delegate().pollLast();
      }
    }

    @Override
    public E getFirst() {
      synchronized (mutex) {
        return delegate().getFirst();
      }
    }

    @Override
    public E getLast() {
      synchronized (mutex) {
        return delegate().getLast();
      }
    }

    @CheckForNull
    public E pollLast() {
      synchronized (mutex) {
        return delegate().pollLast();
      }
    }

    @Override
    public E getFirst() {
      synchronized (mutex) {
        return delegate().getFirst();
      }
    }

    @Override
    public E getLast() {
      synchronized (mutex) {
        return delegate().getLast();
      }
    }

   * @return the first element of {@code iterable} or the default value
   * @since 7.0
   */
  @ParametricNullness
  public static <T extends @Nullable Object> T getFirst(
      Iterable<? extends T> iterable, @ParametricNullness T defaultValue) {
    return Iterators.getNext(iterable.iterator(), defaultValue);
  }

  /**

                    logger.warn("DefaultHttpClient does not have {}.", propertyName);
                }
            }
        }

        formSchemeList.forEach(p -> {
            final FormScheme scheme = p.getFirst();
            final Credentials credentials = p.getSecond();
            scheme.authenticate(credentials, (request, consumer) -> {

                // request header

    <T> void clearReferenceQueue(ReferenceQueue<T> referenceQueue) {
      while (referenceQueue.poll() != null) {}
    }

    /** Returns first entry of bin for given hash. */
    @CheckForNull
    E getFirst(int hash) {
      // read this volatile field only once
      AtomicReferenceArray<E> table = this.table;
      return table.get(hash & (table.length() - 1));
    }

    <T> void clearReferenceQueue(ReferenceQueue<T> referenceQueue) {
      while (referenceQueue.poll() != null) {}
    }

    /** Returns first entry of bin for given hash. */
    @CheckForNull
    E getFirst(int hash) {
      // read this volatile field only once
      AtomicReferenceArray<E> table = this.table;
      return table.get(hash & (table.length() - 1));
    }

    }
  }

  /**
   * Returns the next element in {@code iterator} or {@code defaultValue} if the iterator is empty.
   * The {@link Iterables} analog to this method is {@link Iterables#getFirst}.
   *
   * @param defaultValue the default value to return if the iterator is empty
   * @return the next element of {@code iterator} or the default value
   * @since 7.0
   */
  @ParametricNullness

        if (weight > 0) {
          return e;
        }
      }
      throw new AssertionError();
    }

    /** Returns first entry of bin for given hash. */
    ReferenceEntry<K, V> getFirst(int hash) {
      // read this volatile field only once
      AtomicReferenceArray<ReferenceEntry<K, V>> table = this.table;
      return table.get(hash & (table.length() - 1));
    }

        "addAll(n, allPresent) should return true",
        getList().addAll(0, MinimalCollection.of(e0())));
    expectAdded(0, e0());
  }

  @ListFeature.Require(absent = SUPPORTS_ADD_WITH_INDEX)
  @CollectionSize.Require(absent = ZERO)
  public void testAddAllAtIndex_unsupportedAllPresent() {
    assertThrows(
        UnsupportedOperationException.class, () -> getList().addAll(0, MinimalCollection.of(e0())));
    expectUnchanged();
  }

   */
  public void testAddAtIndex_unsupportedPresent() {
    assertThrows(UnsupportedOperationException.class, () -> getList().add(0, e0()));
    expectUnchanged();
  }

  @ListFeature.Require(SUPPORTS_ADD_WITH_INDEX)
  public void testAddAtIndex_supportedNotPresent() {
    getList().add(0, e3());
    expectAdded(0, e3());
  }

  @CollectionFeature.Require(FAILS_FAST_ON_CONCURRENT_MODIFICATION)