private int getAbsoluteIndex(int index) {
    if (index < 0 || this.firstIndex + index >= this.lastIndexExclusive) {
      throw new ArrayIndexOutOfBoundsException(index);
    }
    return this.firstIndex + index;
  }
Returns Gets the walEdit for the operation(Mutation) at the specified position.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MiniBatchOperationInProgress.java