Where is io.sockets.adapter.rooms in io of nodejs?

https://stackoverflow.com/a/6727354/462608

The short answer:
io.sockets.adapter.rooms

I analysed io:

The sockets output part from io as shown in that answer contains the following:

sockets: 
   { manager: [Circular],
     name: '',
     sockets: { '210837319844898486': [Object] },
     auth: false,
     flags: { endpoint: '', exceptions: [] },
     _events: { connection: [Function] } },

Where is the adapter? Where are the rooms?

What is the way to find out adapter and rooms from the output of io?

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