how to register a custom json marshaller in grails

I am trying to register a custom json marshaller like this

 JSON.createNamedConfig("dynamic",{ 
            def m = new CustomJSONSerializer()
            JSON.registerObjectMarshaller(Idf, 1, { instance, converter -> m.marshalObject(instance, converter) }) 
            })

and then using it like this

    JSON.use("dynamic"){
            render inventionList as JSON
            }

but I am not sure if my custom serializer is being used because when I am debugging control never goes to marshalObject function of my custom serializer

My custom serializer is as follows

import grails.converters.deep.JSON
import java.beans.PropertyDescriptor
import java.lang.reflect.Field
import java.lang.reflect.Method
import org.codehaus.groovy.grails.web.converters.exceptions.ConverterException
import org.codehaus.groovy.grails.web.converters.marshaller.json.GroovyBeanMarshaller
import org.codehaus.groovy.grails.web.json.JSONWriter

class CustomJSONSerializer extends GroovyBeanMarshaller{
    public boolean supports(Object object) {
        return object instanceof GroovyObject;
    }

    public void marshalObject(Object o, JSON json) throws ConverterException {
        JSONWriter writer = json.getWriter();
        println 'properties '+BeanUtils.getPropertyDescriptors(o.getClass())
        for(PropertyDescriptor property:BeanUtils.getProperyDescriptors(o.getClass())){
                println 'property '+property.getName()
            }
        try {
            writer.object();
            for (PropertyDescriptor property : BeanUtils.getPropertyDescriptors(o.getClass())) {
                String name = property.getName();
                Method readMethod = property.getReadMethod();
                if (readMethod != null && !(name.equals("metaClass")) && readMethod.getName()!='getSpringSecurityService') {
                    Object value = readMethod.invoke(o, (Object[]) null);