public class Foo
{
..
    private Foo1 foo1;
    // maybe List listOfFoo1;
..
}

public class Foo1
{
...
    private Foo2 foo2;
    // maybe List listOfFoo2;
...
}

public class Foo2
{
...
    private Foo2 foo3;
    //maybe List listOfFoo3;
...
}

select foo from Foo foo
    inner join foo.foo1 foo1
    inner join foo1.foo2 foo2
    inner join foo2.foo3 foo3
where foo3.service = "Y"

select foo from Foo foo
where foo.foo1.foo2.foo3.service = "Y"

inner join foo.listOfFoo1 listOfFoo1Element