Datenwerke ReportServer, trouble adding custom Data Source (Caché)

I'm working with Datenwerke ReportServer. I'm trying to consume a Caché source via DJBC. Here is a blog post from them on adding additional databases. Unfortunately, I don't fully understand it. I have the JDBC file in the right place and I have created a groovy script for Caché which is below. The problem is related to the weird Query Wrapper thing it does. I can successfully test the datasource via the ReportServer UI, but when I try to execute a simple query, I get the following error:

Error

Query could not be prepared: Error preparing statement for executing the report query : SELECT * FROM (SELECT * FROM (SELECT TOP 10 * FROM HS_IHE_ATNA_Repository.Aggregation) wrappedQry) limitQry LIMIT 50 OFFSET 0 /* token: 6aab148a-927b-45d5-9dfd-724788e139ca / / currentuser: 3 */

cache.groovy

package databasehelper;

import net.datenwerke.rs.scripting.service.scripting.scriptservices.GlobalsWrapper;
import net.datenwerke.rs.base.service.dbhelper.DatabaseHelper
import net.datenwerke.rs.base.service.dbhelper.hooks.DatabaseHelperProviderHook
import net.datenwerke.rs.base.service.dbhelper.queries.Query
import net.datenwerke.rs.base.service.dbhelper.querybuilder.ColumnNamingService
import net.datenwerke.rs.base.service.dbhelper.querybuilder.QueryBuilder

class Cache extends DatabaseHelper {

    public static final String DB_NAME = "Cache";
    public static final String DB_DRIVER = "com.intersys.jdbc.CacheDriver";
    public static final String DB_DESCRIPTOR = "DBHelper_Cache";

    @Override
    public String getDescriptor() {
        return DB_DESCRIPTOR;
    }

    @Override
    public String getDriver() {
        return DB_DRIVER;
    }

    @Override
    public String getName() {
        return DB_NAME;
    }

    @Override
    public String createDummyQuery() {
    return 'SELECT * FROM HS_IHE_ATNA_Repository.Aggregation'
    }

}


def HOOK_NAME = "DATASOURCE_HELPER_Cache"

def callback =  [
            provideDatabaseHelpers : {
                return Collections.singletonList(new Cache());
            }
        ] as DatabaseHelperProviderHook;

GLOBALS.services.callbackRegistry.attachHook(HOOK_NAME, DatabaseHelperProviderHook.class, callback)

Seems like a longshot posting this here, especially with

Notice generated query:

SELECT * FROM (SELECT * FROM 
(SELECT TOP 10 * FROM HS_IHE_ATNA_Repository.Aggregation) 
wrappedQry) limitQry LIMIT 50 OFFSET 0

Caché SQL does not support LIMIT and OFFSET.

%VID and TOP can be used in Caché SQL instead of LIMIT / OFFSET: http://docs.intersystems.com/cache20152/csp/docbook/DocBook.UI.Page.cls?KEY=GSQL_views#GSQL_C13474