@CanIgnoreReturnValue
  public GsonBuilder setStrictness(Strictness strictness) {
    this.strictness = Objects.requireNonNull(strictness);
    return this;
  }
@Test
  public void testSetStrictness() throws IOException {
    final Strictness STRICTNESS = Strictness.STRICT;
    GsonBuilder builder = new GsonBuilder();
    builder.setStrictness(STRICTNESS);
    Gson gson = builder.create();
    assertThat(gson.newJsonReader(new StringReader("{}")).getStrictness()).isEqualTo(STRICTNESS);
    assertThat(gson.newJsonWriter(new StringWriter()).getStrictness()).isEqualTo(STRICTNESS);
  }