code: @BetaApi
    public final Policy getIamPolicyInstance(ProjectZoneInstanceResourceName resource) {
  
      GetIamPolicyInstanceHttpRequest request =
          GetIamPolicyInstanceHttpRequest.newBuilder()
              .setResource(resource == null ? null : resource.toString())
              .build();
      return getIamPolicyInstance(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 (InstanceClient instanceClient = InstanceClient.create()) {
  ProjectZoneInstanceResourceName resource = ProjectZoneInstanceResourceName.of("[PROJECT]", "[ZONE]", "[RESOURCE]");
  Policy response = instanceClient.getIamPolicyInstance(resource);
  }
  </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