IMap-Listener module misses classes given in lab

I am currently following the [In memory computing essentials course](https://training.hazelcast.com/path/hazelcast-developer-essentials-50/in-memory-computing-essentials). I wanted to try out the labs given in the [lab guide](https://training.hazelcast.com/path/hazelcast-developer-essentials-50/in-memory-computing-essentials/581178).
In the 2nd lab, which concerns entry listeners, the code skeleton for the lab is said to be in `IMap-Listener/src/main/java/hazelcast` but I can't find the following classes, even though they are listed in the lab:
- `ListeningMember`
- `ModifyingMember`

There is no `Solutions` package either, everything seems to have disappeared in the commit 756af2191cd3d90034fa1b55a2c3cec9dbe9ae9b but was not restored afterwards.

I could restore the classes but I'm not sure about the intent behind that commit so I'm just creating an issue for now. Maybe the lab wording is not up-to-date.

Start in IMap-Listener/src/main/java/hazelcast and compare the current contents with commit 756af2191cd3d90034fa1b55a2c3cec9dbe9ae9b, focusing on ListeningMember, ModifyingMember, and the missing Solutions package. Check the linked lab guide to determine whether the classes should be restored or the lab wording updated; done means the repository and lab describe the same available files.

Written by the indexing model from the issue text.