@Override
		public boolean hasNext() {
			try {
				if (refIter != null && refIter.hasNext()) {
					return true;
				}
				Address fromAddr = fromIter.next();
				refIter = null;
				// Looping handles possibility of concurrent modification
				while (fromAddr != null && refIter == null) {
					RefList refList = getFromRefs(fromAddr);
					if (refList != null) {
						refIter = refList.getRefs();
					}
					else {
						fromAddr = fromIter.next();
					}
				}
			}
			catch (IOException e) {
				program.dbError(e);
			}
			return (refIter != null);
		}
Construct a reference iterator sorted on the from address.
@param set set of from addresses
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/references/ReferenceDBManager.java