in src/main/java/org/apache/sling/superimposing/impl/SuperimposingManagerImpl.java [421:425]
public Iterator<SuperimposingResourceProvider> getRegisteredProviders() {
List<SuperimposingResourceProvider> resourceProviders = superimposingProviders.values().stream()
.map(srp -> (SuperimposingResourceProvider) srp).collect(Collectors.toList());
return IteratorUtils.unmodifiableIterator(resourceProviders.iterator());
}