private byte findHighestRefLevel(byte currentRefLevel) throws IOException {
		byte maxLevel = (byte) -1;
		ReferenceIterator it = getRefs();
		while (it.hasNext()) {
			Reference ref = it.next();
			byte level = getRefLevel(ref.getReferenceType());
			if (maxLevel < level) {
				maxLevel = level;
			}
			if (level >= currentRefLevel) {
				return level;
			}
		}
		return maxLevel;
	}
Construct reference list for existing record
@param rec existing refList record
@param adapter entry record storage adapter
@param addrMap address map for encoding/decoding addresses
@param program associated Program
@param cache RefList object cache
@param isFrom true for from-adapter use, false for to-adapter use
@throws IOException if database IO error occurs
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/references/BigRefListV0.java