The method lookupElementOfType in the resource provider (e.g., the PCMURIResourceProvider) is described to Looks up an ECore element with the given class type. However, this only works with root level elements, e.g., Repository, or system model. It does not work recursively with all contained elements (at least in my tests):

resourceProvider.lookupElementOfType(RepositoryPackage.eINSTANCE.getRepository()); // This works and returns the repository
resourceProvider.lookupElementOfType(RepositoryPackage.eINSTANCE.getBasicComponent()); // This returns an empty list

Not only would this feature help when quickly scanning through models, it's also unintuitive as lookupElementWithId also works with all non top-level elements.

TL;DR: Please make lookupElementOfType find all elements 🚀