@Override
	public void processEvent(PluginEvent event) {

		if (event instanceof TreeSelectionPluginEvent) {
			TreeSelectionPluginEvent ev = (TreeSelectionPluginEvent) event;
			String treeName = ev.getTreeName();
			TreeViewProvider provider = providerMap.get(treeName);
			if (provider == null) {
				return;
			}
			provider.setGroupSelection(ev.getGroupPaths());
		}
		else {
			super.processEvent(event);
		}
	}
Read the data for the plugin upon deserialization; reads what should be
the current selection in the tree.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/programtree/ProgramTreePlugin.java