Splunk logback/log4j appender does not seem to log splunk

[raivivan]

I need to log to splunk from AWS Lambda using Java8 runtime. It uses spring framework and I added logback splunk appender to the project. There are no errors and the logs don't seem to show up in splunk. The splunk admin mentioned that there are no requests received on splunk server. When I tried to invoke the REST API manually, the log show up in splunk. So the connectivity from AWS Lambda to splunk server is good. The splunk appender seem to be invoking the API in async fashion and I added a 50seconds sleep at the end of the AWS Lambda code to see whether it is an issue with VM exiting before the async step completes. No luck yet. How do I debug further?