Basic Synology

Looks like you cannot use a SysOID map on this one as the system ID is "Linux", then you have to check for the DSM system MIB.  This can be done in a propertysource.  I cloned the one for snmpUptime, set applies to as "hasCategory("snmp") && isLinux()" and tweaked to check for the DSM system status OID (2R2Y3E):

// import the logicmonitor snmp helper class
import com.santaba.agent.groovyapi.snmp.Snmp;

// get the snmp host from the device properties
def host = hostProps.get('system.hostname');

// retrieve the value for the specified OID
try 
{
    oid_value = Snmp.get(host, ".1.3.6.1.4.1.6574.1.1.0");
}
catch (Exception ex)
{
    oid_value = null;
}

// output the value
if (oid_value)
{
    println "system.categories=SynologyDSM";
}

// return with a response code that indicates we ran successfully
return (0);