Oh sure, sorry for my forget.
Try datomic.samples.Functions#main in java 8 and 11, it is executed successfully for java 8 but there is an error described above for java 11.
To get Caused by: java.util.concurrent.ExecutionException: java.lang.ClassCastException: class org.codehaus.commons.compiler.jdk.ScriptEvaluator cannot be cast to class org.codehaus.commons.compiler.jdk.ClassBodyEvaluator please use datomic-pro instead of datomic-free