PropertyHandle :: IsOwner - Is Property Handle owner of the data source

The function returns true (YES), when the property handle is the only user of the data source handle, i.e. when the data source handle is closed when closing the property handle.

When the data source is shared by several property handles, the data source handle is shared by several property handles, the last property handle closed will destroy the data source handle. as long as several property handles share the data source handle, no property handle is considered as owner.