Disparate tests show failures because classes/packages created by the "Compiler" test harness and added to the classpath by the JShell.addToClasspath() mechanism are not seen on the classpath on subsequent accesses.

Since it can't be reproduced, it is unclear if this is an issue with addToClasspath or a filesystem or "Compiler" timing issue.

With JDK-8165405, JShell.addToClasspath is no longer used by the tool and the test infrastructure that used it now uses a completely different mechanism. However, it is still in the API and API tests have been seen to fail.