See http://mail.openjdk.java.net/pipermail/jigsaw-dev/2017-March/011871.html

Caused by: java.lang.IllegalAccessException: class
sun.reflect.misc.Trampoline cannot access class
com.mechanitis.demo.sense.client.user.TwitterUser (in module
com.mechanitis.demo.sense.client) because module
com.mechanitis.demo.sense.client does not export
com.mechanitis.demo.sense.client.user to unnamed module @779d6cc6
at
java.base/jdk.internal.reflect.Reflection.throwIllegalAccessException(Reflection.java:423)
at
java.base/jdk.internal.reflect.Reflection.throwIllegalAccessException(Reflection.java:414)
at
java.base/jdk.internal.reflect.Reflection.ensureMemberAccess(Reflection.java:112)
at
java.base/java.lang.reflect.AccessibleObject.slowCheckMemberAccess(AccessibleObject.java:632)
at
java.base/java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:624)
at java.base/java.lang.reflect.Method.invoke(Method.java:539)
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:72)
at jdk.internal.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:547)
at java.base/sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:261)
at
javafx.base/com.sun.javafx.property.PropertyReference.getProperty(PropertyReference.java:198)
... 48 more