private void mapResultsToLatestLibs() {
		SymbolTable latestSymbolManager = latestPgm.getSymbolTable();
		String[] latestNames = latestExtMgr.getExternalLibraryNames();
		for (String latestName : latestNames) {
			Symbol librarySymbol = latestSymbolManager.getLibrarySymbol(latestName);
			long latestID = librarySymbol.getID();
			long resultID;
			try {
				resultID = getResultIDFromLatestID(latestID);
			}
			catch (NoValueException e) {
				resultID = latestID;
			}
			if (resultID != -1) {
				resultToLatestMap.put(resultID, latestID);
			}
		}
	}
Populate the reverse map for the Library symbols in the Latest program.
Ghidra/Features/Base/src/main/java/ghidra/app/merge/listing/ExternalProgramMerger.java