@Override
  public boolean isStorageEmpty() {
    if (storage.isEmpty()) {
      return parent == null || parent.isStorageEmpty();
    }
    return false;
  }
Does this account have any storage slots that are set to non-zero values?

@return true if the account has no storage values set to non-zero values. False if any storage
    is set.
evm/src/test/java/org/hyperledger/besu/evm/toy/ToyAccount.java