Groovy- merging an object with another existing object without explicitly mapping properties

merged-object.groovy

class BulkResponse {
    String subject;
}
bulkResponse = new BulkResponse(subject:'Hi Rohit!')

//--

class ThreadResponse extends BulkResponse {
    String campaignName;
}

// -- approach 1

threadResponse = new ThreadResponse(campaignName: 'My Campaign')

bulkResponse.properties.each {
  threadResponse.metaClass[it.key] = it.value
}

println threadResponse.getCampaignName() //My Campaign
println threadResponse.getSubject()      //Hi Rohit!

//-- approach 2

private def getObjectProperties(Object object) {
 object.properties.findAll { k, v -> k != 'class' }
}

ThreadResponse threadResponse2 = getObjectProperties(bulkResponse)
threadResponse2.setCampaignName('My Campaign 2')

println threadResponse2.getCampaignName() //My Campaign 2
println threadResponse2.getSubject()      //Hi Rohit!