core/src/main/java/com/orientechnologies/orient/core/storage/impl/local/OMicroTransaction.java
public void rollback() {
    if (!active)
      throw error("Inactive micro-transaction on rollback");
    if (level < 1)
      throw error("Unbalanced micro-transaction, level = " + level);

    --level;

    if (level == 0) {
      active = false;
      doRollback();
    }
  }
public void rollback() {
    if (!active)
      throw error("Inactive micro-transaction on rollback");
    if (level < 1)
      throw error("Unbalanced micro-transaction, level = " + level);

    --level;

    if (level == 0) {
      active = false;
      doRollback();
    }
  }
Rollbacks the micro-transaction if it's a top-level micro-transaction.