//Class to generate a JSON body
public class generateBodyClass {

    public String getRequestBody(List<Element__c> elementRecords) {
        List<JSONRecordInterface> jsonRecords = new List<JSONRecordInterface>();
        for ( Element__c rec : elementRecords) {
            String action = rec.Action__c;
            String entity = rec.Object_Name__c;
            String recordId = rec.Record_Id__c;

            List<EntityVersions__mdt> mappings = [SELECT DeveloperName, version__c FROM EntityVersions__mdt];
            Map<String, String> entityVersions = new Map<String, String>();
            for(EntityVersions__mdt mdt : mappings) {
                entityVersions.put(mdt.DeveloperName, mdt.version__c);
            }
            JSONRecordInterface obj = (JSONRecordInterface) Type.forName(entityVersions.get(entity)).newInstance();
            jsonRecords.add(obj.returnStructure(entity, action, recordId));
        }
        return JSON.serialize(jsonRecords);
    }


}