* @author Chris Povirk
 * @since 2.0
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public final class Sets {
  private Sets() {}

  /**
   * {@link AbstractSet} substitute without the potentially-quadratic {@code removeAll}
   * implementation.
   */
  abstract static class ImprovedAbstractSet<E extends @Nullable Object> extends AbstractSet<E> {
    @Override

   *       .where(new TypeParameter<V>() {}, valueType);
   * }
   * }</pre>
   *
   * @param <X> The parameter type
   * @param typeParam the parameter type variable
   * @param typeArg the actual type to substitute
   */
  /*
   * TODO(cpovirk): Is there any way for us to support TypeParameter instances for type parameters
   * that have nullable bounds? Unfortunately, if we change the parameter to TypeParameter<? extends

    TypeToken<Map<String, Integer>> reserialized =
        reserialize(new TypeToken<Map<String, Integer>>() {});
    assertEquals(reserialized, substitute(reserialized, String.class));
  }

  private static <T, X> TypeToken<T> substitute(TypeToken<T> type, Class<X> arg) {
    return type.where(new TypeParameter<X>() {}, arg);
  }

   *     errorMessageArgs[0]}, etc. Unmatched arguments will be appended to the formatted message in
   *     square braces. Unmatched placeholders will be left as-is.
   * @param errorMessageArgs the arguments to be substituted into the message template. Arguments
   *     are converted to strings using {@link String#valueOf(Object)}.
   * @throws IllegalArgumentException if {@code expression} is false
   */
  public static void checkArgument(

   *     errorMessageArgs[0]}, etc. Unmatched arguments will be appended to the formatted message in
   *     square braces. Unmatched placeholders will be left as-is.
   * @param errorMessageArgs the arguments to be substituted into the message template. Arguments
   *     are converted to strings using {@link String#valueOf(Object)}.
   * @throws IllegalArgumentException if {@code expression} is false
   */
  public static void checkArgument(

    TypeToken<Map<String, Integer>> reserialized =
        reserialize(new TypeToken<Map<String, Integer>>() {});
    assertEquals(reserialized, substitute(reserialized, String.class));
  }

  private static <T, X> TypeToken<T> substitute(TypeToken<T> type, Class<X> arg) {
    return type.where(new TypeParameter<X>() {}, arg);
  }