SELECT * FROM [scheme:type] AS t WHERE LOWER(t.multiValue) = 'lowercase'

class Runner {

    public static void main(String[] args) throws Exception {
        Session session = getSession();
        prepareRepository(session);

        createNode(new MyValueObject("1", new String[] {"A", "B"}), session);
        createNode(new MyValueObject("2", new String[] {"C", "b"}), session);
        session.save();
        session.logout();

        Session session2 = getSession();
        javax.jcr.query.Query query = session2.getWorkspace().getQueryManager().createQuery("select * from [namespace:mymixin] as m WHERE LOWER(m.titles) = 'b'", javax.jcr.query.Query.JCR_SQL2);
        QueryResult queryResult = query.execute();
        assert queryResult.getRows().getSize() == 2;
        session2.logout();
    }

    static private void prepareRepository(Session session) throws RepositoryException {
        session.getWorkspace().getNamespaceRegistry().registerNamespace("namespace", "http://blah.com/blah/blah");
        NodeTypeManager manager= session.getWorkspace().getNodeTypeManager();
        NodeTypeTemplate template = manager.createNodeTypeTemplate();
        template.setName("namespace:mymixin");
        template.setQueryable(true);
        template.setAbstract(false);
        template.setMixin(true);
        manager.registerNodeType(template, false);
    }

    static  private Node createNode(MyValueObject vo, Session session) throws RepositoryException {

        final Node node;
        node = session.getRootNode().addNode(vo.getId());
        node.addMixin("namespace:mymixin");

        node.setProperty("titles", vo.getTitles());
        return node;
    }

    private static Session getSession() //Create new JCR Session

    static class MyValueObject {
        private final String id;

        private final String[] titles;

        public MyValueObject(String id, String[] titles) {
            this.id = id;
            this.titles = titles;
        }

        public String getId() {
            return id;
        }

        public String[] getTitles() {
            return titles;
        }
    }
}