private void closeProjectData() {
		if (projectData != null) {
			projectData.close();
		}
		projectData = null;
		refObject = null;
	}
Close associated {@link ProjectData} when all consumers have released wrapped object.
Underlying project data instance may remain active until all open project files have been
released/closed.
Ghidra/Framework/Project/src/main/java/ghidra/framework/protocol/ghidra/GhidraURLWrappedContent.java