@Override
	public Icon getIcon(File file) {
		if (FS_ROOT_INFO.isRoot(file)) {
			return FS_ROOT_INFO.getRootIcon(file);
		}
		Icon result = (file != null && file.exists())
				? fileIconMap.computeIfAbsent(file, this::getSystemIcon)
				: null;
		return (result != null) ? result : PROBLEM_FILE_ICON;
	}
This is a cache of file icons, as returned from the OS's file icon service.
<p>
This cache is cleared each time a directory is requested (via 
{@link #getListing(File, FileFilter)} so that any changes to a file's icon are visible the 
next time the user hits refresh or navigates into a directory.
Ghidra/Framework/Docking/src/main/java/docking/widgets/filechooser/LocalFileChooserModel.java