Groovy script to stop pipeline

I want to stop a streamsets pipeline by creating a custom event using Groovy evaluator. I have an http origin stage which gives a json response. I need to have a groovy which reads the json response and create a custom event when final record is reached. I need to write the records to a file till the final record reached. I don’t have a option to create event in http origin stage. Any help on this is appreciated.