docs: public double getMeasure(String additionalMeasureName) {
      if (additionalMeasureName.compareToIgnoreCase("measureMaxDepth") == 0) {
        return measureMaxDepth();
      } else if (additionalMeasureName.compareToIgnoreCase("measureTreeSize") == 0) {
        return measureTreeSize();
      } else if (additionalMeasureName.compareToIgnoreCase("measureNumLeaves") == 0) {
        return measureNumLeaves();
      }  else {
        throw new IllegalArgumentException(additionalMeasureName
            + " not supported (KDTree)");
      }
    }