in src/main/scala/org/apache/spark/sql/datasketches/theta/types/ThetaSketchWrapper.scala [27:32]
def serialize(): Array[Byte] = {
if (updateSketch.isDefined) return updateSketch.get.compact().toByteArrayCompressed
else if (compactSketch.isDefined) return compactSketch.get.toByteArrayCompressed
else if (union.isDefined) return union.get.getResult.toByteArrayCompressed
null
}