Neo4j Events

Consider a class like this

class A {
	List<B> bs;

Assume that we call on an object "aInstance" of class A in OGM. Are PRE_SAVE events of all the saving objects (including aInstance, objects in list bs, etc.) issued before actually starting to save any of them? Or we only know that PRE_SAVE of each object is issued before saving that object? If all PRE_SAVEs are issued before all savings, we may be able to use events for handling this.