Corrected the setup of contact paths for subscribers #22991

The initial contact paths should be assumed as published as that's what client subscribers will receive upon subscription. Any changes to contact points are a delta to that.

akka-cluster-tools/src/main/scala/akka/cluster/client/ClusterClient.scala

@@ -337,7 +337,7 @@ final class ClusterClient(settings: ClusterClientSettings) extends Actor with Ac
   var contacts = initialContactsSel
   sendGetContacts()
 
-  var contactPathsPublished = HashSet.empty[ActorPath]
+  var contactPathsPublished = contactPaths
 
   var subscribers = Vector.empty[ActorRef]
 

akka-cluster-tools/src/multi-jvm/scala/akka/cluster/client/ClusterClientSpec.scala

@@ -326,6 +326,38 @@ class ClusterClientSpec extends MultiNodeSpec(ClusterClientSpec) with STMultiNod
       enterBarrier("after-5")
     }
 
+    "report a removal of a receptionist" in within(10 seconds) {
+      runOn(client) {
+        val unreachableContact = node(client) / "system" / "receptionist"
+        val expectedRoles = Set(first, second, third, fourth)
+        val expectedContacts = expectedRoles.map(node(_) / "system" / "receptionist")
+
+        // We need to slow down things otherwise our receptionists can sometimes tell us
+        // that our unreachableContact is unreachable before we get a chance to
+        // subscribe to events.
+        expectedRoles.foreach { role ⇒
+          testConductor.blackhole(client, role, Direction.Both).await
+        }
+
+        val c = system.actorOf(ClusterClient.props(
+          ClusterClientSettings(system).withInitialContacts(expectedContacts + unreachableContact)), "client5")
+
+        val probe = TestProbe()
+        c.tell(SubscribeContactPoints, probe.ref)
+
+        expectedRoles.foreach { role ⇒
+          testConductor.passThrough(client, role, Direction.Both).await
+        }
+
+        within(10.seconds) {
+          awaitAssert {
+            probe.expectMsgType[ContactPointRemoved].contactPoint should ===(unreachableContact)
+          }
+        }
+      }
+      enterBarrier("after-7")
+    }
+
     "re-establish connection to another receptionist when server is shutdown" in within(30 seconds) {
       runOn(first, second, third, fourth) {
         val service2 = system.actorOf(Props(classOf[TestService], testActor), "service2")
@@ -415,7 +447,7 @@ class ClusterClientSpec extends MultiNodeSpec(ClusterClientSpec) with STMultiNod
         system.stop(c)
       }
 
-      enterBarrier("after-7")
+      enterBarrier("after-8")
     }
 
     "re-establish connection to receptionist after server restart" in within(30 seconds) {