Boiler plate when iterating through collections

Beginne mit der Implementierung von PageIterator in com.microsoft.graph.core.tasks.PageIterator.java, insbesondere mit extractEntityListFromParsable und dem Iterationspfad zwischen den Seiten, und überprüfe anschließend den Abschnitt zu PageIterator in docs/upgrade-to-v6.md. Stelle das generische Delta-Beispiel aus dem Issue nach und ermittle, ob Anforderungen für Collections und Delta-Collections einen kompakten Iterator gemeinsam nutzen können; als erledigt gilt die Aufgabe, wenn das unterstützte Verhalten und die erforderliche API-Änderung klar sind.

Hello, i have a small question.

https://github.com/microsoftgraph/msgraph-sdk-java/blob/dev/docs/upgrade-to-v6.md#pageiterator

• With the new page iterator there is a boilerplate associated with each request and iterating through it. Since a new page iterator would need to be created for each request.
• I was wondering if there is a generic way to create an iterator to run on collection requests and delta collection requests.

So I created this code, from looking at the generated code in the msft graph sdk:

  public static <T extends Parsable> void genericIterator(
      GraphServiceClient graphClient,
      BaseDeltaFunctionResponse res,
      Consumer<T> processEntity, 
      Consumer<String> processDeltaLink) {
    PageIterator<T, BaseDeltaFunctionResponse> pageIterator;
    try {
      pageIterator = new PageIterator.Builder<T, BaseDeltaFunctionResponse>()
              .client(graphClient)
              .collectionPage(res)
              .collectionPageFactory(BaseDeltaFunctionResponse::createFromDiscriminatorValue)
              .processPageItemCallback(entity -> {
                processEntity.accept(entity);
                return true; 
              }).build();
      pageIterator.iterate();
      processDeltaLink.accept(pageIterator.getDeltaLink());
    } catch (ApiException | ReflectiveOperationException e) {
      log.error("Error ", e);
    }
  }

  public static <T extends Parsable> void genericIterator(
      GraphServiceClient graphClient,
      BaseCollectionPaginationCountResponse res,
      Consumer<T> processGroupOwner) {
    PageIterator<T, BaseCollectionPaginationCountResponse> pageIterator;
    try {
      pageIterator = new PageIterator.Builder<T, BaseCollectionPaginationCountResponse>()
              .client(graphClient)
              .collectionPage(res)
              .collectionPageFactory(BaseCollectionPaginationCountResponse::createFromDiscriminatorValue)
              .processPageItemCallback(entity -> {
                processGroupOwner.accept(entity);
                return true; 
              }).build();
      pageIterator.iterate();
    } catch (ApiException | ReflectiveOperationException e) {
      log.error("Error ", e);
    }
  }

This second method works with general collectors, but not the first one for delta collections.

I was wondering if this is even recommending considering that the sdk is based on code generations and/or if there is a way to iterate over collections in a more concise manner than the current page iterator.

Error received from the generic delta collection iterator:

DeltaGetResponse res2 = graphServiceClient.groups().delta().get();
genericIterator(graphServiceClient, res2, (Group group) -> {
  log.info("Group: {} {}", group.getId(), group.getDisplayName());
}, (String deltaLink) -> {
  log.info("DeltaLink: {}", deltaLink);
});

java.lang.IllegalAccessException: NO_COLLECTION_PROPERTY_ERROR
        at com.microsoft.graph.core.tasks.PageIterator.extractEntityListFromParsable(PageIterator.java:300)
        at com.microsoft.graph.core.tasks.PageIterator.interpageIterate(PageIterator.java:250)
        at com.microsoft.graph.core.tasks.PageIterator.iterate(PageIterator.java:272)