Migration of dialect to Hibernate 6

Hibernate ORM
2

There is no easy way, but I think you don’t need registerHibernateType anymore. As for registerFunction, I’d suggest you rather introduce a org.hibernate.boot.model.FunctionContributor:

public class MyFunctionContributor imlements org.hibernate.boot.model.FunctionContributor {
    public void contributeFunctions(FunctionContributions functionContributions) {
        functionContributions.getFunctionRegistry().registerAlternateKey("group_concat", "listagg");
        functionContributions.getFunctionRegistry().registerPattern("match_against", "match (?1) against (?2 in boolean mode)", functionContributions.getTypeConfiguration().getBasicTypeRegistry().resolve(StandardBasicTypes.DOUBLE));
    }
}

Note that you also need a file META-INF/services/org.hibernate.boot.model.FunctionContributor that contains the fully qualified class name of MyFunctionContributor.