AWS allows to create Lambda function with Java 8
(OpenJDK 8) as runtime.
I need to create a simple function using Open JDK 1
There's no longer a need to use a custom runtime, as AWS Lambda now supports Java 11.
However, Lambda functions that use this runtime will be run with Amazon Corretto 11 and not OpenJDK 11.
If you wish to run your Lambda function with OpenJDK 11 instead of Corretto 11, then using a custom runtime is still recommended.