Properties and property bindings introduced in Java 8 are extremely useful programming concepts. They are especially useful when you are developing user interfaces. In fact they are so useful that developers have fallen victim to the idea that everything should be a property instead of a primitive. Unfortunately they easily forget that properties such as SimpleLongProperty are much bigger objects than standard types such as Long. And of course they are much bigger than primitive data types such as long.
In one of my current projects pretty much every model object used by the client is composed of properties. For many of these model objects it is the right approach because they will be edited / modified via JavaFX controls. But there are also many model objects that are not edited. They exist to support the rendering of schedules in the FlexGantt