Sets the value of a managed reference.
                    Can be set when when propertyType is SerializedPropertyType.ManagedReference. This property is Write Only (you cannot read from it). 
 
                    The value object must be a type that is compatible with the base type of the managed reference field (that is, the managed reference field that the serialized property is referencing).
                    See Also: propertyType, SerializedPropertyType.ManagedReference.