Always set initialNodeId

Author: GalLalouche

server/src/main/java/org/elasticsearch/tasks/TaskManager.java

@@ -21,6 +21,7 @@
 import org.elasticsearch.cluster.ClusterStateApplier;
 import org.elasticsearch.cluster.node.DiscoveryNode;
 import org.elasticsearch.cluster.node.DiscoveryNodes;
+import org.elasticsearch.common.UUIDs;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.ByteSizeValue;
 import org.elasticsearch.common.util.concurrent.AbstractRunnable;
@@ -48,6 +49,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
@@ -80,8 +82,7 @@ public class TaskManager implements ClusterStateApplier {
 
     private TaskResultsService taskResultsService;
 
-    /** Should be set in tests where the lastDiscoveryNodes might not be updated before the first task is registered. */
-    private final @Nullable String initialNodeId;
+    private final String initialNodeId;
     private DiscoveryNodes lastDiscoveryNodes = DiscoveryNodes.EMPTY_NODES;
 
     private final Tracer tracer;
@@ -98,7 +99,7 @@ public TaskManager(Settings settings, ThreadPool threadPool, Set<String> taskHea
     }
 
     public TaskManager(Settings settings, ThreadPool threadPool, Set<String> taskHeaders, Tracer tracer) {
-        this(settings, threadPool, taskHeaders, tracer, null);
+        this(settings, threadPool, taskHeaders, tracer, UUIDs.randomBase64UUID());
     }
 
     public TaskManager(Settings settings, ThreadPool threadPool, Set<String> taskHeaders, Tracer tracer, @Nullable String initialNodeId) {
@@ -148,9 +149,7 @@ public Task register(String type, String action, TaskAwareRequest request, boole
                 headers.put(key, httpHeader);
             }
         }
-        String lastDiscoveryNodeId = lastDiscoveryNodes.getLocalNodeId();
-        String localNodeId = lastDiscoveryNodeId != null ? lastDiscoveryNodeId : initialNodeId;
-        assert localNodeId != null : "lastDiscoveryNodes is not set, and no initialNodeId was provided";
+        String localNodeId = Optional.ofNullable(lastDiscoveryNodes.getLocalNodeId()).orElse(initialNodeId);
         Task task = request.createTask(
             new TaskId(localNodeId, taskIdGenerator.incrementAndGet()),
             type,