@Test
public void isWildcardType() {

  assertThat(Types.isWildcardType(STRING)).isFalse();
  TypeToken<?> t = new TypeToken<Collection<?>>() {};
  assertThat(Types.isWildcardType(
      t.resolveType(((ParameterizedType) t.getType()).getActualTypeArguments()[0]))).isTrue();
  t = new TypeToken<Collection<? extends String>>() {};
  assertThat(Types.isWildcardType(
      t.resolveType(((ParameterizedType) t.getType()).getActualTypeArguments()[0]))).isTrue();
}