import java.util.stream.Collectors;

class Utils {
    static <T> T nonNull(T t) {
        if (t == null) {
            throw new IllegalArgumentException();
        }
        return t;
    }

    static <T> T nonNull(T t, String name) {
        if (t == null) {
            throw new IllegalArgumentException(name + " cannot be null");
        }
        return t;
    }

    static <T> T cast(Class<T> clazz, Object o, String name) {

  public <T> void testWhere_incompatibleGenericArrayMapping() {
    assertThrows(
        IllegalArgumentException.class,
        () -> new TypeResolver().where(new TypeCapture<T[]>() {}.capture(), String.class));
  }

  public <T> void testWhere_incompatibleParameterizedTypeMapping() {
    assertThrows(
        IllegalArgumentException.class,
        () -> new TypeResolver().where(new TypeCapture<Iterable<T>>() {}.capture(), List.class));

  }

  @Test fun addThrowsOnEmptyName() {
    assertFailsWith<IllegalArgumentException> {
      Headers.Builder().add(": bar")
    }
    assertFailsWith<IllegalArgumentException> {
      Headers.Builder().add(" : bar")
    }
  }

  @Test fun addThrowsOnNoColon() {
    assertFailsWith<IllegalArgumentException> {
      Headers.Builder().add("foo bar")
    }
  }

   * Entries appear in the result {@code ImmutableBiMap} in encounter order.
   *
   * <p>If the mapped keys or values contain duplicates (according to {@link
   * Object#equals(Object)}), an {@code IllegalArgumentException} is thrown when the collection
   * operation is performed. (This differs from the {@code Collector} returned by {@link
   * Collectors#toMap(Function, Function)}, which throws an {@code IllegalStateException}.)
   *

    if (!safe) {
      throw conflictException(conflictDescription, entry1, entry2);
    }
  }

  static IllegalArgumentException conflictException(
      String conflictDescription, Object entry1, Object entry2) {
    return new IllegalArgumentException(
        "Multiple entries with same " + conflictDescription + ": " + entry1 + " and " + entry2);
  }

  /**

   * elements. The generated map is sorted by the specified comparator.
   *
   * <p>If the mapped keys contain duplicates (according to the specified comparator), an {@code
   * IllegalArgumentException} is thrown when the collection operation is performed. (This differs
   * from the {@code Collector} returned by {@link Collectors#toMap(Function, Function)}, which
   * throws an {@code IllegalStateException}.)
   *

    // By default, parallel edges are not allowed.
    IllegalArgumentException e =
        assertThrows(IllegalArgumentException.class, () -> directedGraph.addEdge(N1, N2, E12_A));
    assertThat(e.getMessage()).contains(ERROR_PARALLEL_EDGE);

    // By default, self-loop edges are not allowed.
    e = assertThrows(IllegalArgumentException.class, () -> directedGraph.addEdge(N1, N1, E11));

          ToOptionalState::getOptional,
          Collector.Characteristics.UNORDERED);

  /**
   * A collector that converts a stream of zero or one elements to an {@code Optional}.
   *
   * @throws IllegalArgumentException if the stream consists of two or more elements.
   * @throws NullPointerException if any element in the stream is {@code null}.
   * @return {@code Optional.of(onlyElement)} if the stream has exactly one element (must not be

        if (relativeSource.isAbsolute()) {
            throw new IllegalArgumentException("Supplied URI is not relative");
        }
        URI source = baseURI.resolve(relativeSource);
        if (!source.toASCIIString().startsWith(baseURI.toASCIIString())) {
            throw new IllegalArgumentException("Supplied relative URI escapes baseUrl");
        }
        GetTask getTask = new GetTask(source);

    network.addNode(N1);
    network.addNode(N2);
    IllegalArgumentException e =
        assertThrows(
            IllegalArgumentException.class,
            () -> networkForTest.edgesConnecting(N1, NODE_NOT_IN_GRAPH));
    assertNodeNotInGraphErrorMessage(e);
    e =
        assertThrows(
            IllegalArgumentException.class,
            () -> networkForTest.edgesConnecting(NODE_NOT_IN_GRAPH, N2));