@Override
  public Object terminate() {
    double sum = ((Number) super.terminate()).doubleValue();
    double result = sum / distinct.size();
    return downCast(result);
  }
Computes the final average of distinct values for the partitioned region based queries. This
aggregator is initialized on the PR query node & acts on the results obtained from bucket nodes.
geode-core/src/main/java/org/apache/geode/cache/query/internal/aggregate/AvgDistinctPRQueryNode.java