Add annotation to document if a returned instance is shared across components

Issue #19 resolved
Michael Ludwig
repo owner created an issue

The main place this occurs is in component data types that use an @Unmanaged field to cache values from a lower-level property representation (i.e. taking packed float data and storing them into a Vector3).

Although beneficial for performance, it has consequences if someone holds onto the instance thinking that it is not invalidated when the ComponentData is targeted to another component.