code: @BetaApi
    public final Policy getIamPolicySubnetwork(String resource) {
  
      GetIamPolicySubnetworkHttpRequest request =
          GetIamPolicySubnetworkHttpRequest.newBuilder().setResource(resource).build();
      return getIamPolicySubnetwork(request);
    }
docs: Gets the access control policy for a resource. May be empty if no such policy or resource
  exists.
  
  <p>Sample code:
  
  <pre><code>
  try (SubnetworkClient subnetworkClient = SubnetworkClient.create()) {
  ProjectRegionSubnetworkResourceName resource = ProjectRegionSubnetworkResourceName.of("[PROJECT]", "[REGION]", "[RESOURCE]");
  Policy response = subnetworkClient.getIamPolicySubnetwork(resource.toString());
  }
  </code></pre>
  
  @param resource Name or id of the resource for this request.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails