code: public TransactionWriteRequest addDelete(Object key, DynamoDBTransactionWriteExpression transactionWriteExpression) {
          return addDelete(key, transactionWriteExpression, null /* returnValuesOnConditionCheckFailure */);
      }
docs: Adds delete operation (to be executed on the object represented by key) to the list of transaction write operations.
  transactionWriteExpression is used to conditionally delete the object represented by key.