Clean up CoordinatorTests (#134028)

Fixes IntelliJ suggestions in `action/CoordinatorTests` and
`coordination/CoordinatorTests`

Author: joshua-adams-1

server/src/test/java/org/elasticsearch/cluster/coordination/CoordinatorTests.java

@@ -45,7 +45,6 @@
 import org.elasticsearch.transport.TransportService;
 import org.elasticsearch.xcontent.ToXContent;
 
-import java.io.IOException;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -928,7 +927,7 @@ public TransportVersion getMinimalSupportedVersion() {
             }
 
             @Override
-            public void writeTo(StreamOutput out) throws IOException {
+            public void writeTo(StreamOutput out) {
                 if (timeAdvancer != null) {
                     timeAdvancer.advanceTime();
                 }
@@ -1064,7 +1063,7 @@ public void testJoiningNodeReceivesFullState() {
             cluster.stabilise();
 
             cluster.addNodesAndStabilise(1);
-            final ClusterNode newNode = cluster.clusterNodes.get(cluster.clusterNodes.size() - 1);
+            final ClusterNode newNode = cluster.clusterNodes.getLast();
             final PublishClusterStateStats newNodePublishStats = newNode.coordinator.stats().getPublishStats();
             // initial cluster state send when joining
             assertEquals(1L, newNodePublishStats.getFullClusterStateReceivedCount());
@@ -1289,9 +1288,8 @@ public void testClusterCannotFormWithFailingJoinValidation() throws Exception {
      * @param failJoinOnAllNodes this controls whether to fail join on all nodes or only a majority subset. The atomic register CAS election
      *                           strategy will succeed in electing a master if any node can vote (even the master candidate voting for
      *                           itself).
-     * @throws Exception
      */
-    protected void clusterCannotFormWithFailingJoinValidation(boolean failJoinOnAllNodes) throws Exception {
+    protected void clusterCannotFormWithFailingJoinValidation(boolean failJoinOnAllNodes) {
         try (Cluster cluster = new Cluster(randomIntBetween(1, 5))) {
             List<ClusterNode> clusterNodesToFailJoin;
             if (failJoinOnAllNodes) {
@@ -1593,7 +1591,7 @@ public TransportVersion getMinimalSupportedVersion() {
         }
 
         @Override
-        public void writeTo(StreamOutput out) throws IOException {
+        public void writeTo(StreamOutput out) {
             throw new ElasticsearchException(EXCEPTION_MESSAGE);
         }
 
@@ -1708,9 +1706,9 @@ public void match(LogEvent event) {
                                 .toList();
                             assertThat(matchingNodes, hasSize(1));
 
-                            assertTrue(message, Regex.simpleMatch(discoveryMessageFn.apply(matchingNodes.get(0).toString()), message));
+                            assertTrue(message, Regex.simpleMatch(discoveryMessageFn.apply(matchingNodes.getFirst().toString()), message));
 
-                            nodesLogged.add(matchingNodes.get(0).getLocalNode());
+                            nodesLogged.add(matchingNodes.getFirst().getLocalNode());
                         }
 
                         @Override

x-pack/plugin/enrich/src/test/java/org/elasticsearch/xpack/enrich/action/CoordinatorTests.java

@@ -75,7 +75,7 @@ public void testCoordinateLookups() {
         assertThat(coordinator.queue.size(), equalTo(5));
         assertThat(coordinator.getRemoteRequestsCurrent(), equalTo(1));
         assertThat(lookupFunction.capturedRequests.size(), equalTo(1));
-        assertThat(lookupFunction.capturedRequests.get(0).requests().size(), equalTo(5));
+        assertThat(lookupFunction.capturedRequests.getFirst().requests().size(), equalTo(5));
 
         // Nothing should happen now, because there is an outstanding request and max number of requests has been set to 1:
         coordinator.coordinateLookups();
@@ -93,7 +93,7 @@ public void testCoordinateLookups() {
         emptyResponse.decRef();
         final MultiSearchResponse res1 = new MultiSearchResponse(responseItems, 1L);
         try {
-            lookupFunction.capturedConsumers.get(0).accept(res1, null);
+            lookupFunction.capturedConsumers.getFirst().accept(res1, null);
             assertThat(coordinator.queue.size(), equalTo(0));
             assertThat(coordinator.getRemoteRequestsCurrent(), equalTo(1));
             assertThat(lookupFunction.capturedRequests.size(), equalTo(2));
@@ -149,10 +149,10 @@ public void testCoordinateLookupsMultiSearchError() {
         assertThat(coordinator.queue.size(), equalTo(0));
         assertThat(coordinator.getRemoteRequestsCurrent(), equalTo(1));
         assertThat(lookupFunction.capturedRequests.size(), equalTo(1));
-        assertThat(lookupFunction.capturedRequests.get(0).requests().size(), equalTo(5));
+        assertThat(lookupFunction.capturedRequests.getFirst().requests().size(), equalTo(5));
 
         RuntimeException e = new RuntimeException();
-        lookupFunction.capturedConsumers.get(0).accept(null, e);
+        lookupFunction.capturedConsumers.getFirst().accept(null, e);
         assertThat(coordinator.queue.size(), equalTo(0));
         assertThat(coordinator.getRemoteRequestsCurrent(), equalTo(0));
         assertThat(lookupFunction.capturedRequests.size(), equalTo(1));
@@ -189,7 +189,7 @@ public void testCoordinateLookupsMultiSearchItemError() {
         assertThat(coordinator.queue.size(), equalTo(0));
         assertThat(coordinator.getRemoteRequestsCurrent(), equalTo(1));
         assertThat(lookupFunction.capturedRequests.size(), equalTo(1));
-        assertThat(lookupFunction.capturedRequests.get(0).requests().size(), equalTo(5));
+        assertThat(lookupFunction.capturedRequests.getFirst().requests().size(), equalTo(5));
 
         RuntimeException e = new RuntimeException();
         // Replying a response and that should trigger another coordination round
@@ -199,7 +199,7 @@ public void testCoordinateLookupsMultiSearchItemError() {
         }
         var res = new MultiSearchResponse(responseItems, 1L);
         try {
-            lookupFunction.capturedConsumers.get(0).accept(res, null);
+            lookupFunction.capturedConsumers.getFirst().accept(res, null);
             assertThat(coordinator.queue.size(), equalTo(0));
             assertThat(coordinator.getRemoteRequestsCurrent(), equalTo(0));
             assertThat(lookupFunction.capturedRequests.size(), equalTo(1));
@@ -213,7 +213,7 @@ public void testCoordinateLookupsMultiSearchItemError() {
         }
     }
 
-    public void testNoBlockingWhenQueueing() throws Exception {
+    public void testNoBlockingWhenQueueing() {
         MockLookupFunction lookupFunction = new MockLookupFunction();
         // Only one request allowed in flight. Queue size maxed at 1.
         Coordinator coordinator = new Coordinator(lookupFunction, 1, 1, 1);
@@ -256,11 +256,11 @@ public void testNoBlockingWhenQueueing() throws Exception {
         // Fulfill the captured consumer which will schedule the next item in the queue.
         var res = new MultiSearchResponse(new MultiSearchResponse.Item[] { new MultiSearchResponse.Item(emptySearchResponse(), null) }, 1L);
         try {
-            lookupFunction.capturedConsumers.get(0).accept(res, null);
+            lookupFunction.capturedConsumers.getFirst().accept(res, null);
             // Ensure queue was drained and that the item in it was scheduled
             assertThat(coordinator.queue.size(), equalTo(0));
             assertThat(lookupFunction.capturedRequests.size(), equalTo(2));
-            assertThat(lookupFunction.capturedRequests.get(1).requests().get(0), sameInstance(searchRequest));
+            assertThat(lookupFunction.capturedRequests.get(1).requests().getFirst(), sameInstance(searchRequest));
         } finally {
             res.decRef();
         }
@@ -308,8 +308,8 @@ public ThreadPool threadPool() {
             String index = indices.get(i);
             assertThat(requests.get(i).index(), equalTo(index));
             assertThat(requests.get(i).getMultiSearchRequest().requests().size(), equalTo(2));
-            assertThat(requests.get(i).getMultiSearchRequest().requests().get(0).indices().length, equalTo(1));
-            assertThat(requests.get(i).getMultiSearchRequest().requests().get(0).indices()[0], equalTo(index));
+            assertThat(requests.get(i).getMultiSearchRequest().requests().getFirst().indices().length, equalTo(1));
+            assertThat(requests.get(i).getMultiSearchRequest().requests().getFirst().indices()[0], equalTo(index));
         }
     }