Sealing violation when running repository within Eclipse

When running hippo-ecm-application-reviewed-actions-repository within Eclipse (after setting up as described in http://repodocs.hippocms.org/extending-hippo-ecm/building/eclipse.html), the application throws a SecurityException:

java.lang.SecurityException: sealing violation: package org.apache.derby.iapi.services.crypto is sealed

See attached stacktrace.

The following URL states that this might be caused by loading classes from the same package from different jar files: http://www.nabble.com/Problems-with-Derby-10.2.2.0-t3564887.html