update-value-example.java

public class Foo {
  String word;

  public Foo(String word) {
    this.word = word;
  }
}

public class FooUpdate extends Update<Foo> {
  private Foo newFoo;
  
  public FooUpdate(Foo newFoo)  {
    this.newFoo = newFoo;
  }
  
  public Foo update() {
    return this.newFoo;
  }
  
  @Override
  public T apply(Foo original) {
    return update();
  }
}

// Current value at the key: {"word":"old_word"}

UpdateValue update = new UpdateValue.Builder(location)
        .withUpdate(new FooUpdate(new Foo("new word"))
        .build();