@Override
  public void addEthHashObserver(final PoWObserver observer) {
    if (this.miningCoordinator instanceof PoWMiningCoordinator) {
      miningCoordinator.addEthHashObserver(observer);
    }
  }
Gets merge coordinator.

@return the merge coordinator
consensus/merge/src/main/java/org/hyperledger/besu/consensus/merge/blockcreation/TransitionCoordinator.java