@Override
  public Hash getCodeHash() {
    if (updatedCode == null) {
      // Note that we set code for new account, so it's only null if account isn't.
      return oldCodeHash;
    } else {
      // Cache the hash of updated code to avoid DOS attacks which repeatedly request hash
      // of updated code and cause us to regenerate it.
      if (updatedCodeHash == null) {
        updatedCodeHash = Hash.hash(updatedCode);
      }
      return updatedCodeHash;
    }
  }
A map of the storage entries that were modified.

@return a map containing all entries that have been modified. This <b>may</b> contain entries
    with a value of 0 to signify deletion.
evm/src/main/java/org/hyperledger/besu/evm/worldstate/UpdateTrackingAccount.java