Abstract base class for UnityEvents.
This class provides the base functionality for the UnityEvents.
| GetPersistentEventCount | Get the number of registered persistent listeners. |
| GetPersistentMethodName | Get the target method name of the listener at index index. |
| GetPersistentTarget | Get the target component of the listener at index index. |
| RemoveAllListeners | Remove all non-persistent listeners from the event. |
| SetPersistentListenerState | Modify the execution state of a persistent listener. |
| GetValidMethodInfo | Given an object, function name, and a list of argument types; find the method that matches. |