Why are properties stored in "event.Pro​pertyEvent​.AffectedO​bject" instead of objects?

Listen for Changes to Property Values tell us :Define Callback Function for Property Event

The listener executes the callback function when MATLAB® triggers the property event. Define the callback function to have two specific arguments, which are passed to the function automatically when called by the listener:

• Event source — a meta.property object describing the object that is the source of the property event
• Event data — a event.PropertyEvent object containing information about the event

event.PropertyEvent tell us :Properties----AffectedObject — Object whose property is affected

handle object

Object whose property is affected, specified as the object handle.

So,There should be an object stored in the ’-AffectedObject‘.But the result of code execution is not

Here is an example.make a breakingpoint in ClassB 22th line 'end'.

input in command window

>> obj_a=ClassA;

>> obj_b=ClassB(obj_a);

>> obj_a.y=4;

When program stop in ClassB 22th line .You check“evnt.AffectedObject”,you will find obj-a's property 'x' 'y' is stored here，not ’ obj-a‘

What is object ，include 'property' 'method' 'event'………………，not only the property.

So why are there only properties in ’evnt.AffectedObject‘, but not the full object?

classdef  ClassA < handle
    properties (SetObservable)  %或(SetObservable=true)
        x=1;
        y=2;
    end
    events
        kk
    end
    methods
        function obj=ClassA()
            x=1;
        end
    end
end

classdef  ClassB < handle
    methods
        %构造函数，输入参数event_obj是产生事件的对象
        function obj = ClassB(event_obj)
            %为x的PreSet、为y的PostSet分别添加两个听众
            if nargin > 0
                addlistener(event_obj,'x','PreSet',@ClassB.eventsCBFunc);
                addlistener(event_obj,'y','PostSet',@ClassB.eventsCBFunc);
            end
        end
    end
    methods (Static)
        %两个听众的回调函数
        function eventsCBFunc(src,evnt)
            switch src.Name
                case 'x'
                    fprintf(['Current event:' evnt.EventName]);
                    fprintf(1,' \n x is %s\n',num2str(evnt.AffectedObject.x))
                case 'y'
                    fprintf(['Current event:' evnt.EventName]);
                    fprintf(1,' \n y is %s\n',num2str(evnt.AffectedObject.y))
            end
        end
    end
end