protected NR doOverflowTreatment(NR n, LevelInfo levelInfo) {
		// OT1
		if (n != root && !levelInfo.checkAndSetReinserted()) {
			doReInsert(n, levelInfo);
			return null;
		}
		return doSplit(n);
	}
The Split algorithm as defined in Section 4.2 of the paper.

@param n the node to split
@return the new node (containing the second group)
Ghidra/Debug/ProposedUtils/src/main/java/ghidra/util/database/spatial/AbstractRStarConstraintsTree.java