@Override
	public Long getBaseOffset(int tableIndex) throws PdbException {
		PlaceholderVirtualBaseTableEntry entry = entry(tableIndex);
		Long offset = (entry == null) ? null : entry.getOffset();
		return offset;
	}
Constructor
@param owner the class that owns the table
@param parentage the parentage of the base class(es) of the table
Ghidra/Features/PDB/src/main/java/ghidra/app/util/pdb/classtype/PlaceholderVirtualBaseTable.java