assertThrows(NullPointerException.class, () -> multimap().putAll(source));
    expectUnchanged();
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_KEYS)
  public void testPutAllRejectsNullKey() {
    Multimap<K, V> source = getSubjectGenerator().create(mapEntry(null, v0()));
    assertThrows(NullPointerException.class, () -> multimap().putAll(source));
    expectUnchanged();

    assertThrows(NullPointerException.class, () -> multimap().putAll(source));
    expectUnchanged();
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_KEYS)
  public void testPutAllRejectsNullKey() {
    Multimap<K, V> source = getSubjectGenerator().create(mapEntry(null, v0()));
    assertThrows(NullPointerException.class, () -> multimap().putAll(source));
    expectUnchanged();

        }
    }

    @Test
    void testNullHandling() {
        assertThrows(NullPointerException.class, () -> Sources.fromPath(null));
        assertThrows(NullPointerException.class, () -> Sources.buildSource(null));
        assertThrows(NullPointerException.class, () -> Sources.resolvedSource(null, "modelId"));
    }

    for (LoadingCache<Object, Object> cache : caches()) {
      assertThrows(NullPointerException.class, () -> cache.get(null));
      checkEmpty(cache);
    }
  }

  public void testGetUnchecked_null() {
    for (LoadingCache<Object, Object> cache : caches()) {
      assertThrows(NullPointerException.class, () -> cache.getUnchecked(null));
      checkEmpty(cache);
    }
  }

    for (LoadingCache<Object, Object> cache : caches()) {
      assertThrows(NullPointerException.class, () -> cache.get(null));
      checkEmpty(cache);
    }
  }

  public void testGetUnchecked_null() {
    for (LoadingCache<Object, Object> cache : caches()) {
      assertThrows(NullPointerException.class, () -> cache.getUnchecked(null));
      checkEmpty(cache);
    }
  }

  private enum ExceptionTypePolicy {

    /**
     * Exceptions should be {@link NullPointerException} or {@link UnsupportedOperationException}.
     */
    NPE_OR_UOE() {
      @Override
      public boolean isExpectedType(Throwable cause) {
        return cause instanceof NullPointerException
            || cause instanceof UnsupportedOperationException;
      }
    },

    /**

    private Sources() {}

    /**
     * Creates a new source for the specified path.
     *
     * @param path the path to the file
     * @return a new Source instance
     * @throws NullPointerException if path is null
     */
    @Nonnull
    public static Source fromPath(@Nonnull Path path) {
        return new PathSource(requireNonNull(path, "path"));
    }

    /**

    }
    expectUnchanged();
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_KEYS)
  public void testPutIfAbsent_nullKeyUnsupported() {
    assertThrows(NullPointerException.class, () -> getMap().putIfAbsent(null, v3()));
    expectUnchanged();
    expectNullKeyMissingWhenNullKeysUnsupported(
        "Should not contain null key after unsupported putIfAbsent(null, value)");
  }

   * Stream.of(stream1, stream2, ...).flatMap(s -> s)}. If the sources are iterables, use {@code
   * Stream.of(iter1, iter2, ...).flatMap(Streams::stream)}.
   *
   * @throws NullPointerException if any of the provided iterables is {@code null}
   * @since 20.0
   */
  @SafeVarargs
  public static <T extends @Nullable Object> FluentIterable<T> concat(
      Iterable<? extends T>... inputs) {

  public void testNullListener() {
    assertThrows(NullPointerException.class, () -> future.addListener(null, directExecutor()));
  }

  public void testNullExecutor() {
    assertThrows(NullPointerException.class, () -> future.addListener(doNothing(), null));
  }

  public void testNullTimeUnit() throws Exception {
    future.set(1);
    assertThrows(NullPointerException.class, () -> future.get(0, null));
  }