private void buildDescritors() {
    for (SketchDescriptor sketchDescriptor : sketchClasses.values()) {
      descriptors.addAll(sketchDescriptor.fnMap.values());
    }
  }
Registers functions from the DataSketches library as builtin functions.

In an effort to show a more consistent
ql/src/java/org/apache/hadoop/hive/ql/exec/DataSketchesFunctions.java