How to send formatted json logs to logstash?

We are printing the logs in json format in K8 kernel from where the centralized system reading though logstash Agent.
{"app":"Svc","@timestamp":"2020-10-05T07:25:37.575Z","logger":"com.ljec.service.impl.LjecServiceImpl","level":"ERROR","class":"com.reporting.ljec.service.implLjecServiceImpl","method":"getLjecEntitiesCount","file":"LjecServiceImpl.java","line":640,"thread":"http-nio-8080-exec-1","message":"Error accessing elastic search","dmzID":"sw.nan@XXX.com"}
The above log coming as a message string in kibana.I want this to be consumed as JSON by logstash agent. Where can i put the json filter to read by logagent as JSON?