The base class for all history events.
A history event contains data about an event that has happened in a process instance. Such an event may be the start of an activity, the end of an activity, a task instance that is created or other similar events...
History events contain data in a serializable form. Some implementations may persist events directly or may serialize them as an intermediate representation for later processing (ie. in an asynchronous implementation).
This class implements {@link DbEntity}. This was chosen so that {@link HistoryEvent}s can be easily persisted using the {@link DbEntityManager}. This may not be used by all {@link HistoryEventHandler}implementations but it does also not cause harm.
@author Daniel Meyer