public TrieLogLayer addAccountChange(
      final Address address, final AccountValue oldValue, final AccountValue newValue) {
    checkState(!frozen, "Layer is Frozen");
    accounts.put(address, new PathBasedValue<>(oldValue, newValue));
    return this;
  }
Locks the layer so no new changes can be added;
ethereum/core/src/main/java/org/hyperledger/besu/ethereum/trie/pathbased/common/trielog/TrieLogLayer.java