Development Assistance Arraylist/HashMap Help

Hello so what I am trying to do is make a way for players to store chunk inside of a config. Basically making what I thought was a simple chunk claiming plugin. So what I want is for player to be able to claim chunks and when they claim chunks they will be stored in the config as:

Player:
Chunk_ids:
- 1
- 2
- 3
- 4

but even further I need to store as:

Player:
Chunk_ids:
1:
X:
Z:
2:
X:
Z:
So if you find the time could you please help me. Please explain with some matter of detail as it has been awhile since I coded last.