client = monitoring.Client()
metric = 'compute.googleapis.com/instance/cpu/utilization'
query_results = client.query(metric, minutes=5).iter(headers_only=True)
for result in query_results:
    print(result)

MetricServiceClient metricServiceClient = MetricServiceClient.create();
String projectId = System.getProperty("projectId");
ProjectName name = ProjectName.create(projectId);

// Restrict time to last 20 minutes
long startMillis = System.currentTimeMillis() - ((60 * 20) * 1000);
TimeInterval interval = TimeInterval.newBuilder()
    .setStartTime(Timestamps.fromMillis(startMillis))
    .setEndTime(Timestamps.fromMillis(System.currentTimeMillis()))
    .build();

ListTimeSeriesRequest.Builder requestBuilder = ListTimeSeriesRequest.newBuilder()
    .setNameWithProjectName(name)
    .setFilter("metric.type=\"compute.googleapis.com/instance/cpu/utilization\"")
    .setInterval(interval)
    .setView(ListTimeSeriesRequest.TimeSeriesView.HEADERS);

ListTimeSeriesRequest request = requestBuilder.build();

PagedResponseWrappers.ListTimeSeriesPagedResponse response = metricServiceClient
    .listTimeSeries(request);

System.out.println("Got timeseries headers: ");
for (TimeSeries ts : response.iterateAll()) {
  System.out.println(ts);
}