code: public Observable<ServiceResponse<Page<ManagedInstanceKeyInner>>> listByInstanceWithServiceResponseAsync(final String resourceGroupName, final String managedInstanceName, final String filter) {
          return listByInstanceSinglePageAsync(resourceGroupName, managedInstanceName, filter)
              .concatMap(new Func1<ServiceResponse<Page<ManagedInstanceKeyInner>>, Observable<ServiceResponse<Page<ManagedInstanceKeyInner>>>>() {
                  @Override
                  public Observable<ServiceResponse<Page<ManagedInstanceKeyInner>>> call(ServiceResponse<Page<ManagedInstanceKeyInner>> page) {
                      String nextPageLink = page.body().nextPageLink();
                      if (nextPageLink == null) {
                          return Observable.just(page);
                      }
                      return Observable.just(page).concatWith(listByInstanceNextWithServiceResponseAsync(nextPageLink));
                  }
              });
      }
docs: Gets a list of managed instance keys.
  
  @param resourceGroupName The name of the resource group that contains the resource. You can obtain this value from the Azure Resource Manager API or the portal.
  @param managedInstanceName The name of the managed instance.
  @param filter An OData filter expression that filters elements in the collection.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;ManagedInstanceKeyInner&gt; object