RPi3 Mining Node Wallet Address Configuration
Support for the built-in CPU miner was removed in Bitcoin Core v0.13 (see https://bitcoin.org/en/release/v0.13.0#removal-of-internal-miner), so this issue is moot.

Historically speaking, the built in miner asked the built-in wallet for an address. So it was not configurable - you just had to use the internal wallet RPC to manage the funds you got out of mining.