* cases where {@link Collection#contains} might throw {@link NullPointerException} or {@link
   * ClassCastException}.
   */
  // <? extends @Nullable Object> instead of <?> because of Kotlin b/189937072, discussed in Joiner.
  public static boolean contains(
      Iterable<? extends @Nullable Object> iterable, @CheckForNull Object element) {
    if (iterable instanceof Collection) {

     * platforms we target.
     *
     * 2. Kotlin's Map type has a getOrDefault method that accepts and returns a "plain V," in
     * contrast to the "V?" type that we're using. As a result, Kotlin sees a conflict between the
     * nullness annotations in ImmutableMap and those in its own Map type. In response, it considers
     * the parameter and return type both to be platform types. As a result, Kotlin permits calls