private SourceType checkExternalLabel(String extLabel, Address extAddr, SourceType source)
			throws InvalidInputException {
		if (StringUtils.isBlank(extLabel) ||
			SymbolUtilities.isReservedExternalDefaultName(extLabel, addrMap.getAddressFactory())) {
			extLabel = null; // force use of address
		}
		if (extLabel == null && extAddr == null) {
			throw new InvalidInputException("Either an external label or address is required");
		}
		return extLabel == null ? SourceType.DEFAULT : source;
	}
Constructs a new ExternalManagerDB
@param handle the open database handle
@param addrMap the address map
@param openMode the program open mode.
@param lock the program synchronization lock
@param monitor the progress monitor used when upgrading
@throws CancelledException if the user cancelled while an upgrade was occurring
@throws IOException if a database io error occurs.
@throws VersionException if the database version does not match the expected version
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/external/ExternalManagerDB.java