@Override
	public T get(Address addr) {
		validate(lock);
		Table table = propertyTable;
		if (table == null) {
			return null;
		}
		long addrKey = addrMap.getKey(addr, false);
		if (addrKey == AddressMap.INVALID_ADDRESS_KEY) {
			return null;
		}
		return cache.computeIfAbsent(addrKey, valueReader);
	}
Attempt to upgrade the map table records to the current schema.
If unable to upgrade any of the map records, the table is removed.
@param tokenInstance token saveable instance
@param monitor task monitor
@return true if all records were successfully upgrade.  A false
value indicates that one or more entries were dropped.
@throws CancelledException if task is cancelled
@throws IOException if IO error occurs
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/properties/ObjectPropertyMapDB.java