PdbVirtualBaseTable createVirtualBaseTable(Address address, int entrySize) {

		VirtualBaseTable vbt = vbtByAddress.get(address);
		if (vbt != null) {
			String message =
				"PDB: warning virtual base table already exists for address: " + address;
			PdbLog.message(message);
			Msg.info(this, message);
		}
		else {
			vbt = new PdbVirtualBaseTable(memory, address, entrySize);
			vbtByAddress.put(address, vbt);
		}
		if (!(vbt instanceof PdbVirtualBaseTable)) {
			// investigate this
		}
		return (PdbVirtualBaseTable) vbt;
	}
//	 * Builds the tables
//	 * @throws PdbException If Program is null;
//	 * @throws CancelledException upon user cancellation.
//
Ghidra/Features/PDB/src/main/java/ghidra/app/util/pdb/pdbapplicator/PdbVbtManager.java