List<AssertionBuilder<Element>> customAssertionBuilders = new ArrayList<AssertionBuilder<Element>>();
customAssertionBuilders.add(new GCMAlgorithmSuiteBuilder());
PolicyEnforcer policyEnforcer = buildAndStartPolicyEngine(policyString, false, customAssertionBuilders);
OperationSecurityEvent operationSecurityEvent = new OperationSecurityEvent();
operationSecurityEvent.setOperation(new QName("definitions"));
policyEnforcer.registerSecurityEvent(operationSecurityEvent);
AlgorithmSuiteSecurityEvent algorithmSuiteSecurityEvent = new AlgorithmSuiteSecurityEvent();
algorithmSuiteSecurityEvent.setAlgorithmURI(WSSConstants.NS_XENC11_AES256_GCM);
algorithmSuiteSecurityEvent.setKeyLength(256);