code: public Observable<Page<PoolUsageMetrics>> listUsageMetricsNextAsync(final String nextPageLink, final PoolListUsageMetricsNextOptions poolListUsageMetricsNextOptions) {
          return listUsageMetricsNextWithServiceResponseAsync(nextPageLink, poolListUsageMetricsNextOptions)
              .map(new Func1<ServiceResponseWithHeaders<Page<PoolUsageMetrics>, PoolListUsageMetricsHeaders>, Page<PoolUsageMetrics>>() {
                  @Override
                  public Page<PoolUsageMetrics> call(ServiceResponseWithHeaders<Page<PoolUsageMetrics>, PoolListUsageMetricsHeaders> response) {
                      return response.body();
                  }
              });
      }
docs: Lists the usage metrics, aggregated by pool across individual time intervals, for the specified account.
  If you do not specify a $filter clause including a poolId, the response includes all pools that existed in the account in the time range of the returned aggregation intervals. If you do not specify a $filter clause including a startTime or endTime these filters default to the start and end times of the last aggregation interval currently available; that is, only the last aggregation interval is returned.
  
  @param nextPageLink The NextLink from the previous successful call to List operation.
  @param poolListUsageMetricsNextOptions Additional parameters for the operation
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;PoolUsageMetrics&gt; object