There are many failure like this one that prevent us from running the test suite (both client-server and library) with JDK 1.6:

https://jenkins.mw.lab.eng.bos.redhat.com/hudson/view/JDG/view/FUNC/job/edg-60-ispn-testsuite-rhel/USE_JDK=JDK6,jdk=java17_default,label=RHEL6_x86_64/400/testReport/org.infinispan.xsite.backupfailure/OptDistBackupFailureTest/createBeforeClass/


Caused by: java.lang.NoSuchMethodError: java.lang.Long.compare(JJ)I
	at org.jgroups.util.TimeScheduler3$Task.compareTo(TimeScheduler3.java:260)
	at org.jgroups.util.TimeScheduler3$Task.compareTo(TimeScheduler3.java:237)
	at java.util.PriorityQueue.siftUpComparable(PriorityQueue.java:582)
	at java.util.PriorityQueue.siftUp(PriorityQueue.java:574)
	at java.util.PriorityQueue.offer(PriorityQueue.java:274)
	at java.util.concurrent.DelayQueue.offer(DelayQueue.java:86)
	at java.util.concurrent.DelayQueue.add(DelayQueue.java:71)
	at java.util.concurrent.DelayQueue.add(DelayQueue.java:39)
	at org.jgroups.util.TimeScheduler3.add(TimeScheduler3.java:211)
	at org.jgroups.util.TimeScheduler3.doSchedule(TimeScheduler3.java:190)
	at org.jgroups.util.TimeScheduler3.scheduleRecurring(TimeScheduler3.java:176)
	at org.jgroups.util.TimeScheduler3.scheduleWithFixedDelay(TimeScheduler3.java:99)
	at org.jgroups.protocols.TP.init(TP.java:1205)
	at org.jgroups.protocols.BasicTCP.init(BasicTCP.java:84)
	at org.jgroups.stack.ProtocolStack.initProtocolStack(ProtocolStack.java:860)
	at org.jgroups.stack.ProtocolStack.setup(ProtocolStack.java:481)
	at org.jgroups.JChannel.init(JChannel.java:848)
	at org.jgroups.JChannel.<init>(JChannel.java:159)
	at org.jgroups.JChannel.<init>(JChannel.java:139)
	at org.infinispan.remoting.transport.jgroups.JGroupsTransport.buildChannel(JGroupsTransport.java:392)
	at org.infinispan.remoting.transport.jgroups.JGroupsTransport.initChannel(JGroupsTransport.java:284)
	at org.infinispan.remoting.transport.jgroups.JGroupsTransport.initChannelAndRPCDispatcher(JGroupsTransport.java:328)
	at org.infinispan.remoting.transport.jgroups.JGroupsTransport.start(JGroupsTransport.java:188)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.infinispan.commons.util.ReflectionUtil.invokeAccessibly(ReflectionUtil.java:168)
	... 35 more