@Override
  public UpdateSchema makeColumnOptional(String name) {
    internalUpdateColumnRequirement(name, true);
    return this;
  }
@Test
  public void testMakeColumnOptional() {
    Schema schema = new Schema(required(1, "id", Types.IntegerType.get()));
    Schema expected = new Schema(optional(1, "id", Types.IntegerType.get()));

    Schema result = new SchemaUpdate(schema, 1).makeColumnOptional("id").apply();

    assertThat(result.asStruct()).isEqualTo(expected.asStruct());
  }