public interface HibernateSqlFunctionRegistrar {

    default void registerFunction(Map<String, SQLFunction> sqlFunctions, String name, SQLFunction function) {
        // HHH-7721: SQLFunctionRegistry expects all lowercase. Enforce,
        // just in case a user's customer dialect uses mixed cases.
        sqlFunctions.put(name.toLowerCase(Locale.ROOT), function);
    }

    Map<String, SQLFunction> getSqlFunctions(Dialect dialect);

}

public class HibernateSpringIntegrator
        implements MetadataBuilderInitializer, ApplicationContextAware {

    private static ApplicationContext applicationContext;

    /** The Constant log. */
    private static final Logger log = LoggerFactory.getLogger(HibernateSpringIntegrator.class);

    @Override
    public void contribute(final MetadataBuilder metadataBuilder, final StandardServiceRegistry serviceRegistry) {
        log.info("Registering custom SQL functions"); //$NON-NLS-1$
        try {
            Map<String, HibernateSqlFunctionRegistrar> registars =
                    HibernateSpringIntegrator.applicationContext.getBeansOfType(HibernateSqlFunctionRegistrar.class);
            String dialectClassname =
                    HibernateSpringIntegrator.applicationContext.getBean("jpaProperties", Properties.class)
                            .getProperty("hibernate.dialect");
            Dialect dialect = (Dialect) Class.forName(dialectClassname).newInstance();
            registars.forEach((beanname, registrar) -> {
                Class<?> listenerClass = AopUtils.getTargetClass(registrar);
                log.debug("Registering: {}", listenerClass); //$NON-NLS-1$
                registrar.getSqlFunctions(dialect).forEach((name, sqlFunction) -> {
                    metadataBuilder.applySqlFunction(name, sqlFunction);
                });
            });
        } catch (RuntimeException e) {
            throw e;
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
}

public class GCOSqlFunctionRegistrar implements HibernateSqlFunctionRegistrar {

    @Override
    public Map<String, SQLFunction> getSqlFunctions(Dialect dialect) {
        Map<String, SQLFunction> sqlFunctions = new HashMap<>();
        if (dialect instanceof HSQLDialect) {
            registerFunction(sqlFunctions, "get_action_status",
                    new StandardSQLFunction("get_action_status", StandardBasicTypes.STRING));
        } else if (dialect instanceof Oracle12cDialect) {
            registerFunction(sqlFunctions, "get_action_status",
                    new StandardSQLFunction("somepkg.get_action_status", StandardBasicTypes.STRING));
        }
        return sqlFunctions;
    }

}