*
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  @CheckForNull
  public final Entry<K, V> pollFirstEntry() {
    throw new UnsupportedOperationException();
  }

  /**

      throw new UnsupportedOperationException();
    }

    @Override
    public boolean putAll(@ParametricNullness K key, Iterable<? extends V> values) {
      throw new UnsupportedOperationException();
    }

    @Override
    public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
      throw new UnsupportedOperationException();
    }

    @Override

     *
     * @throws UnsupportedOperationException always
     * @deprecated Unsupported operation.
     */
    @CanIgnoreReturnValue
    @Deprecated
    @Override
    @DoNotCall("Always throws UnsupportedOperationException")
    public final boolean add(@ParametricNullness E e) {
      throw new UnsupportedOperationException();
    }

    /**

      fail("no exception thrown");
    } catch (UnsupportedOperationException expected) {
    }
    try {
      iterator.set("a");
      fail("no exception thrown");
    } catch (UnsupportedOperationException expected) {
    }
    try {
      iterator.add("a");
      fail("no exception thrown");
    } catch (UnsupportedOperationException expected) {
    }
  }

    @Override
    public void remove() {
      checkRemove(false);
    }
  }

  /**
   * Returns the empty {@code Iterator} that throws {@link IllegalStateException} instead of {@link
   * UnsupportedOperationException} on a call to {@link Iterator#remove()}.
   */
  // Casting to any type is safe since there are no actual elements.
  @SuppressWarnings("unchecked")