code: public Observable<Page<DatabaseAccountInner>> listByResourceGroupAsync(String resourceGroupName) {
          return listByResourceGroupWithServiceResponseAsync(resourceGroupName).map(new Func1<ServiceResponse<List<DatabaseAccountInner>>, Page<DatabaseAccountInner>>() {
              @Override
              public Page<DatabaseAccountInner> call(ServiceResponse<List<DatabaseAccountInner>> response) {
                  PageImpl<DatabaseAccountInner> page = new PageImpl<>();
                  page.setItems(response.body());
                  return page;
              }
          });
      }
docs: Lists all the Azure Cosmos DB database accounts available under the given resource group.
  
  @param resourceGroupName Name of an Azure resource group.
  @return the observable to the List&lt;DatabaseAccountInner&gt; object