@Override
  public AggregationBuffer getNewAggregationBuffer() throws HiveException {
    if (expectedEntries < 0) {
      throw new IllegalStateException("expectedEntries not initialized");
    }
    return new Aggregation(expectedEntries);
  }
class for storing the current aggregate value.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/aggregates/VectorUDAFBloomFilter.java