code: public final ListGroupStatsPagedResponse listGroupStats(
        ProjectName projectName, QueryTimeRange timeRange) {
      ListGroupStatsRequest request =
          ListGroupStatsRequest.newBuilder()
              .setProjectName(projectName == null ? null : projectName.toString())
              .setTimeRange(timeRange)
              .build();
      return listGroupStats(request);
    }
docs: Lists the specified groups.
  
  <p>Sample code:
  
  <pre><code>
  try (ErrorStatsServiceClient errorStatsServiceClient = ErrorStatsServiceClient.create()) {
  ProjectName projectName = ProjectName.of("[PROJECT]");
  QueryTimeRange timeRange = QueryTimeRange.newBuilder().build();
  for (ErrorGroupStats element : errorStatsServiceClient.listGroupStats(projectName, timeRange).iterateAll()) {
  // doThingsWith(element);
  }
  }
  </code></pre>
  
  @param projectName [Required] The resource name of the Google Cloud Platform project. Written
  as &lt;code&gt;projects/&lt;/code&gt; plus the &lt;a
  href="https://support.google.com/cloud/answer/6158840"&gt;Google Cloud Platform project
  ID&lt;/a&gt;.
  <p>Example: &lt;code&gt;projects/my-project-123&lt;/code&gt;.
  @param timeRange [Optional] List data for the given time range. If not set a default time range
  is used. The field time_range_begin in the response will specify the beginning of this time
  range. Only &lt;code&gt;ErrorGroupStats&lt;/code&gt; with a non-zero count in the given
  time range are returned, unless the request contains an explicit group_id list. If a
  group_id list is given, also &lt;code&gt;ErrorGroupStats&lt;/code&gt; with zero occurrences
  are returned.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails