*       and vice versa. i.e. {@code A.is(B)} and {@code B.is(A)}.
   *   <li>{@code canonicalize(canonicalize(A)) == canonicalize(A)}.
   * </ol>
   */
  private static Type canonicalizeTypeArg(TypeVariable<?> declaration, Type typeArg) {
    return typeArg instanceof WildcardType
        ? canonicalizeWildcardType(declaration, ((WildcardType) typeArg))
        : canonicalizeWildcardsInType(typeArg);
  }