public synchronized List<PolicyProvider> getPolicyProviders() {
resolve();
if (policyProviders == null) {
policyProviders = new ArrayList<PolicyProvider>();
for (PolicyProviderFactory factory : providerFactories.getPolicyProviderFactories()) {
PolicyProvider provider = factory.createReferencePolicyProvider(this);
if (provider != null) {
policyProviders.add(provider);
}
}
}