void unload() {
		// Unregister the listeners.
		// No longer want to listen for changes to previous category.
		if (originalDTM != null) {
			originalDTM.removeDataTypeManagerListener(this);
			originalDTM = null;
		}
		originalDTM = null;
		originalComposite = null;
		originalCompositeId = DataTypeManager.NULL_DATATYPE_ID;
		viewComposite = null;
		originalDataTypePath = null;
		if (viewDTM != null) {
			viewDTM.close();
			viewDTM = null;
		}
	}
Unloads the currently loaded composite data type.
This should be called when the viewer is removed from view and
and category/dataType changes no longer need to be listened for.
It can also be called to unload the current composite before loading
a new composite data type.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/compositeeditor/CompositeViewerModel.java