Collecting and instantiating concrete subclasses of a specified base class. Can be used to collect children for a reference in emf-based editor

CollectConcreteSubclasses.java

/**
 * Iterates over registered ecore packages. Collects and instantiates concrete subclasses. 
 * @return
 */
public static List<MyType> collectMyTypes() {
	List<MyType> ret = new ArrayList<>();
	IExtensionRegistry registry = RegistryFactory.getRegistry();
	if (registry != null) {
		IConfigurationElement[] configElems = registry.getConfigurationElementsFor("org.eclipse.emf.ecore.generated_package");
		for (IConfigurationElement elem : configElems) {
			String uri = elem.getAttribute("uri");
			if (!Util.isBlank(uri)) {
				EPackage epkg = EPackage.Registry.INSTANCE.getEPackage(uri);
				if (epkg != null) {
					for (EClassifier eClassifier: epkg.getEClassifiers()) {
						if (eClassifier instanceof EClass 
								&& !((EClass) eClassifier).isAbstract() 
								&& MyPackage.Literals.MY_TYPE.isSuperTypeOf((EClass) eClassifier)) {
							
							EFactory eFactory = epkg.getEFactoryInstance();
							ret.add((MyType) eFactory.create((EClass) eClassifier));						
						}
					}
				}
			}
		}
	}
	return ret;
}

Using the extension registry to enumerate over all registered packages instead of the package registry because the package registry does not "see" workspace packages when running an Eclipse application from IDE.