public void addProvider(final AuditPrincipalIdProvider provider) {
        if (BeanSupplier.isNotProxy(provider)) {
            providers.add(provider);
        }
    }
Add provider.

@param provider the provider
core/cas-server-core-audit-api/src/main/java/org/apereo/cas/audit/spi/principal/ChainingAuditPrincipalIdProvider.java