code: @BetaApi
    public final Operation setSecurityPolicyBackendService(
        ProjectGlobalBackendServiceName backendService,
        SecurityPolicyReference securityPolicyReferenceResource) {
  
      SetSecurityPolicyBackendServiceHttpRequest request =
          SetSecurityPolicyBackendServiceHttpRequest.newBuilder()
              .setBackendService(backendService == null ? null : backendService.toString())
              .setSecurityPolicyReferenceResource(securityPolicyReferenceResource)
              .build();
      return setSecurityPolicyBackendService(request);
    }
docs: Sets the security policy for the specified backend service.
  
  <p>Sample code:
  
  <pre><code>
  try (BackendServiceClient backendServiceClient = BackendServiceClient.create()) {
  ProjectGlobalBackendServiceName backendService = ProjectGlobalBackendServiceName.of("[PROJECT]", "[BACKEND_SERVICE]");
  SecurityPolicyReference securityPolicyReferenceResource = SecurityPolicyReference.newBuilder().build();
  Operation response = backendServiceClient.setSecurityPolicyBackendService(backendService, securityPolicyReferenceResource);
  }
  </code></pre>
  
  @param backendService Name of the BackendService resource to which the security policy should
  be set. The name should conform to RFC1035.
  @param securityPolicyReferenceResource
  @throws com.google.api.gax.rpc.ApiException if the remote call fails