interface PersonQuery extends Query {
public void setForename(String forename, StringQueryType constraint);
public void setLastname(String lastname, StringQueryType constraint);
}

class Person {
private Long id;
private String forename;
private String lastname;
//… getter and setter.
}

we automatically create the following query object

class PersonQuery implements Query {
public void setForename(String forename, StringQueryType constraint);
public void setLastname(String lastname, StringQueryType constraint);
//…
}

Then with additional helper classes we could perform a query in the following manner:

DataAccess access = factory.getAccess(Person.class);
PersonQuery query = access.getQuery();
query.setForename(”A”, STARTS_WITH);
List result = access.select(query);

All this queries are absolutely type save! And in our case, we were able to formulate all required queries in this way.
I know a build in query system would be more powerfull, but code generation can be also a very powerfull tool. In my opinion code generation is an underestimated technique, maybe because you need a very good integration in your build system. And that is not easy.