@Override
  protected boolean newChainHeadInvalidatesMiningOperation(final BlockHeader newChainHeadHeader) {
    return true;
  }
Responsible for determining when a block mining operation should be started/stopped, then
creating an appropriate miner and starting it running in a thread.
ethereum/blockcreation/src/main/java/org/hyperledger/besu/ethereum/blockcreation/PoWMiningCoordinator.java