public static ParameterizedType setOf(Type elementType) {
    return parameterizedType(Set.class, elementType);
  }
@Test
  public void createSetType() {
    ParameterizedType type = Types.setOf(Person.class);
    assertThat(type.getRawType()).isEqualTo(Set.class);
    assertThat(type.getActualTypeArguments()).isEqualTo(new Type[] {Person.class});
  }