Replace NOT operator with explicit false check (#68124)

Part 3.

We have an in-house rule to compare explicitly against `false` instead
of using the logical not operator (`!`). However, this hasn't
historically been enforced, meaning that there are many violations in
the source at present.

We now have a Checkstyle rule that can detect these cases, but before we
can turn it on, we need to fix the existing violations. This is being
done over a series of PRs, since there are a lot to fix.

Author: pugnascotia

server/src/internalClusterTest/java/org/elasticsearch/action/admin/HotThreadsIT.java

@@ -97,7 +97,7 @@ public void onResponse(NodesHotThreadsResponse nodeHotThreads) {
                         }
                         success = true;
                     } finally {
-                        if (!success) {
+                        if (success == false) {
                             hasErrors.set(true);
                         }
                         latch.countDown();

server/src/internalClusterTest/java/org/elasticsearch/action/bulk/BulkWithUpdatesIT.java

@@ -529,7 +529,7 @@ public void testFailingVersionedUpdatedOnBulk() throws Exception {
 
         int successes = 0;
         for (BulkResponse response : responses) {
-            if (!response.hasFailures()) {
+            if (response.hasFailures() == false) {
                 successes++;
             }
         }

server/src/internalClusterTest/java/org/elasticsearch/action/termvectors/GetTermVectorsIT.java

@@ -219,11 +219,11 @@ public void testSimpleTermVectors() throws IOException {
     }
 
     public static String termVectorOptionsToString(FieldType fieldType) {
-        if (!fieldType.storeTermVectors()) {
+        if (fieldType.storeTermVectors() == false) {
             return "no";
-        } else if (!fieldType.storeTermVectorOffsets() && !fieldType.storeTermVectorPositions()) {
+        } else if (fieldType.storeTermVectorOffsets() == false && fieldType.storeTermVectorPositions() == false) {
             return "yes";
-        } else if (fieldType.storeTermVectorOffsets() && !fieldType.storeTermVectorPositions()) {
+        } else if (fieldType.storeTermVectorOffsets() && fieldType.storeTermVectorPositions() == false) {
             return "with_offsets";
         } else {
             StringBuilder builder = new StringBuilder("with");

server/src/internalClusterTest/java/org/elasticsearch/cluster/allocation/SimpleAllocationIT.java

@@ -49,7 +49,7 @@ public void testSaneAllocation() {
         ClusterState state = client().admin().cluster().prepareState().execute().actionGet().getState();
         assertThat(state.getRoutingNodes().unassigned().size(), equalTo(0));
         for (RoutingNode node : state.getRoutingNodes()) {
-            if (!node.isEmpty()) {
+            if (node.isEmpty() == false) {
                 assertThat(node.size(), equalTo(2));
             }
         }
@@ -60,7 +60,7 @@ public void testSaneAllocation() {
 
         assertThat(state.getRoutingNodes().unassigned().size(), equalTo(0));
         for (RoutingNode node : state.getRoutingNodes()) {
-            if (!node.isEmpty()) {
+            if (node.isEmpty() == false) {
                 assertThat(node.size(), equalTo(1));
             }
         }
@@ -79,7 +79,7 @@ public void testSaneAllocation() {
 
         assertThat(state.getRoutingNodes().unassigned().size(), equalTo(0));
         for (RoutingNode node : state.getRoutingNodes()) {
-            if (!node.isEmpty()) {
+            if (node.isEmpty() == false) {
                 assertThat(node.size(), equalTo(4));
             }
         }

server/src/internalClusterTest/java/org/elasticsearch/gateway/RecoverAfterNodesIT.java

@@ -46,8 +46,7 @@ public Set<ClusterBlock> waitForNoBlocksOnNode(TimeValue timeout, Client nodeCli
         do {
             blocks = nodeClient.admin().cluster().prepareState().setLocal(true).execute().actionGet()
                     .getState().blocks().global(ClusterBlockLevel.METADATA_WRITE);
-        }
-        while (!blocks.isEmpty() && (System.currentTimeMillis() - start) < timeout.millis());
+        } while (blocks.isEmpty() == false && (System.currentTimeMillis() - start) < timeout.millis());
         return blocks;
     }
 

server/src/internalClusterTest/java/org/elasticsearch/index/store/CorruptedFileIT.java

@@ -210,14 +210,14 @@ public void afterIndexShardClosed(ShardId sid, @Nullable IndexShard indexShard,
                     Store store = indexShard.store();
                     store.incRef();
                     try {
-                        if (!Lucene.indexExists(store.directory()) && indexShard.state() == IndexShardState.STARTED) {
+                        if (Lucene.indexExists(store.directory()) == false && indexShard.state() == IndexShardState.STARTED) {
                             return;
                         }
                         BytesStreamOutput os = new BytesStreamOutput();
                         PrintStream out = new PrintStream(os, false, StandardCharsets.UTF_8.name());
                         CheckIndex.Status status = store.checkIndex(out);
                         out.flush();
-                        if (!status.clean) {
+                        if (status.clean == false) {
                             logger.warn("check index [failure]\n{}", os.bytes().utf8ToString());
                             throw new IOException("index check failure");
                         }

server/src/internalClusterTest/java/org/elasticsearch/index/store/ExceptionRetryIT.java

@@ -126,8 +126,8 @@ public void testRetryDueToExceptionOnNetworkLayer() throws ExecutionException, I
         long dupCounter = 0;
         boolean found_duplicate_already = false;
         for (int i = 0; i < searchResponse.getHits().getHits().length; i++) {
-            if (!uniqueIds.add(searchResponse.getHits().getHits()[i].getId())) {
-                if (!found_duplicate_already) {
+            if (uniqueIds.add(searchResponse.getHits().getHits()[i].getId()) == false) {
+                if (found_duplicate_already == false) {
                     SearchResponse dupIdResponse = client().prepareSearch("index").setQuery(termQuery("_id",
                         searchResponse.getHits().getHits()[i].getId())).setExplain(true).get();
                     assertThat(dupIdResponse.getHits().getTotalHits().value, greaterThan(1L));

server/src/internalClusterTest/java/org/elasticsearch/indices/analysis/PreBuiltAnalyzerIntegrationIT.java

@@ -59,7 +59,7 @@ public void testThatPreBuiltAnalyzersAreNotClosedOnIndexClose() throws Exception
             String name = preBuiltAnalyzer.name().toLowerCase(Locale.ROOT);
 
             Version randomVersion = randomVersion(random());
-            if (!loadedAnalyzers.containsKey(preBuiltAnalyzer)) {
+            if (loadedAnalyzers.containsKey(preBuiltAnalyzer) == false) {
                  loadedAnalyzers.put(preBuiltAnalyzer, new ArrayList<Version>());
             }
             loadedAnalyzers.get(preBuiltAnalyzer).add(randomVersion);

server/src/internalClusterTest/java/org/elasticsearch/indices/memory/breaker/CircuitBreakerServiceIT.java

@@ -383,7 +383,7 @@ public void testLimitsRequestSize() {
         // can either fail directly with an exception or the response contains exceptions (depending on client)
         try {
             BulkResponse response = client.bulk(bulkRequest).actionGet();
-            if (!response.hasFailures()) {
+            if (response.hasFailures() == false) {
                 fail("Should have thrown CircuitBreakingException");
             } else {
                 // each item must have failed with CircuitBreakingException

server/src/internalClusterTest/java/org/elasticsearch/indices/stats/IndexStatsIT.java

@@ -408,7 +408,7 @@ public void testThrottleStats() throws Exception {
         // make sure we see throttling kicking in:
         boolean done = false;
         long start = System.currentTimeMillis();
-        while (!done) {
+        while (done == false) {
             for(int i=0; i<100; i++) {
                 // Provoke slowish merging by making many unique terms:
                 StringBuilder sb = new StringBuilder();
@@ -1143,7 +1143,7 @@ public void testConcurrentIndexingAndStatsRequests() throws BrokenBarrierExcepti
                     executionFailures.get().add(e);
                     latch.countDown();
                 }
-                while (!stop.get()) {
+                while (stop.get() == false) {
                     final String id = Integer.toString(idGenerator.incrementAndGet());
                     final IndexResponse response =
                         client()
@@ -1171,7 +1171,7 @@ public void testConcurrentIndexingAndStatsRequests() throws BrokenBarrierExcepti
                 final IndicesStatsRequest request = new IndicesStatsRequest();
                 request.all();
                 request.indices(new String[0]);
-                while (!stop.get()) {
+                while (stop.get() == false) {
                     try {
                         final IndicesStatsResponse response = client().admin().indices().stats(request).get();
                         if (response.getFailedShards() > 0) {