ActivationsSorter: Comparison method violates its general contract! ------------------------------------------------------------------- Key: DROOLS-4866 URL: https://issues.redhat.com/browse/DROOLS-4866 Project: Drools Issue Type: Bug Affects Versions: 7.30.0.Final Environment: - JDK 1.8.0_181 (64 bit) Reporter: Leonid Sotnikov Assignee: Mario Fusco Priority: Major Attachments: sorttest.zip Hi. While serializing a session with ProtobufOutputMarshaller we've encountered an exception in a few rare cases when the activations are sorted by {{Collections.sort( dormant, ActivationsSorter.INSTANCE )}}: {code} Caused by: java.lang.IllegalArgumentException: Comparison method violates its general contract! at java.util.TimSort.mergeHi(TimSort.java:899) at java.util.TimSort.mergeAt(TimSort.java:516) at java.util.TimSort.mergeForceCollapse(TimSort.java:457) at java.util.TimSort.sort(TimSort.java:254) at java.util.Arrays.sort(Arrays.java:1512) at java.util.ArrayList.sort(ArrayList.java:1462) at java.util.Collections.sort(Collections.java:175) (...) {code}