public Set<Address> findTypeinfoRefsPossiblyInVtables(GccTypeinfo typeinfo)
			throws CancelledException {

		Address typeinfoAddr = typeinfo.getAddress();
		Set<Address> typeinfoRefsPossiblyInVtables = new HashSet<Address>();

		Set<Address> typeinfoRefs = directRefMap.get(typeinfoAddr);

		// return emtpy list if no entry in map for given typeinfoAddr
		if (typeinfoRefs == null) {
			return typeinfoRefsPossiblyInVtables;
		}

		for (Address typeinfoRef : typeinfoRefs) {

			Function functionContainingTypeinfoRef =
				program.getListing().getFunctionContaining(typeinfoRef);
			if (functionContainingTypeinfoRef != null) {
				continue;
			}

			Instruction instructionContainingAddr =
				program.getListing().getInstructionContaining(typeinfoRef);
			if (instructionContainingAddr != null) {
				continue;
			}

			Data dataContainingTypeinfoRef =
				program.getListing().getDefinedDataContaining(typeinfoRef);

			if (!isTypeinfoStruct(dataContainingTypeinfoRef)) {
				typeinfoRefsPossiblyInVtables.add(typeinfoRef);
			}
		}

		return typeinfoRefsPossiblyInVtables;
	}
Method to find references to the given typeinfos that are possibly ref'd by
vtables (ie not in functions, other data, etc... and create a map
typeinfoAddress to Set<Address> refs possibly in vtable

@param typeinfos list of GccTypeinfo's
@return map
@throws CancelledException
Ghidra/Features/Decompiler/ghidra_scripts/classrecovery/RTTIGccClassRecoverer.java