code: @BetaApi
    public final ListRegionsPagedResponse listRegions(String project) {
      ListRegionsHttpRequest request =
          ListRegionsHttpRequest.newBuilder().setProject(project).build();
      return listRegions(request);
    }
docs: Retrieves the list of region resources available to the specified project.
  
  <p>Sample code:
  
  <pre><code>
  try (RegionClient regionClient = RegionClient.create()) {
  ProjectName project = ProjectName.of("[PROJECT]");
  for (Region element : regionClient.listRegions(project.toString()).iterateAll()) {
  // doThingsWith(element);
  }
  }
  </code></pre>
  
  @param project Project ID for this request.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails