private RefdFile getFile(String filename, TaskMonitor monitor) {
		try (FileSystemRef fsRef = fsService.getFilesystem(fsFSRL, monitor)) {
			if (fsRef != null) {
				GFileSystem fs = fsRef.getFilesystem();
				String path = FSUtilities.appendPath(subdir, filename);
				GFile file = fs.lookup(path);
				if (file != null && !file.isDirectory()) {
					return new RefdFile(fsRef.dup(), file);
				}
			}
		}
		catch (IOException | CancelledException e) {
			// fall thru
		}
		return null;
	}
Companion to the {@link SameDirSymbolStore}, handles the case where the imported binary
was located in a container file (eg. zip file).
<p>
Instances of this class are conditionally created by the 
{@link SameDirSymbolStore#createInstance(String, SymbolServerInstanceCreatorContext) registry factory method}
when it detects that the imported binary's {@link FSRL} isn't a simple local file.
Ghidra/Features/PDB/src/main/java/pdb/symbolserver/ContainerFileSymbolServer.java