Remove the features supported feature (#119758)

This removes the features_supported feature from the codebase, as all nodes communicable with 9.0 will support features

qa/rolling-upgrade/src/javaRestTest/java/org/elasticsearch/upgrades/ClusterFeatureMigrationIT.java

@@ -1,61 +0,0 @@
-/*
- * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
- * or more contributor license agreements. Licensed under the "Elastic License
- * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
- * Public License v 1"; you may not use this file except in compliance with, at
- * your election, the "Elastic License 2.0", the "GNU Affero General Public
- * License v3.0 only", or the "Server Side Public License, v 1".
- */
-
-package org.elasticsearch.upgrades;
-
-import com.carrotsearch.randomizedtesting.annotations.Name;
-
-import org.elasticsearch.client.Request;
-import org.elasticsearch.common.xcontent.support.XContentMapValues;
-import org.elasticsearch.features.FeatureService;
-import org.junit.Before;
-
-import java.io.IOException;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
-import java.util.stream.Collectors;
-
-import static org.hamcrest.Matchers.empty;
-import static org.hamcrest.Matchers.hasSize;
-
-public class ClusterFeatureMigrationIT extends AbstractRollingUpgradeTestCase {
-
-    @Before
-    public void checkMigrationVersion() {
-        assumeFalse(
-            "This checks migrations from before cluster features were introduced",
-            oldClusterHasFeature(FeatureService.FEATURES_SUPPORTED)
-        );
-    }
-
-    public ClusterFeatureMigrationIT(@Name("upgradedNodes") int upgradedNodes) {
-        super(upgradedNodes);
-    }
-
-    public void testClusterFeatureMigration() throws IOException {
-        if (isUpgradedCluster()) {
-            // check the nodes all have a feature in their cluster state (there should always be features_supported)
-            var response = entityAsMap(adminClient().performRequest(new Request("GET", "/_cluster/state/nodes")));
-            List<?> nodeFeatures = (List<?>) XContentMapValues.extractValue("nodes_features", response);
-            assertThat(nodeFeatures, hasSize(adminClient().getNodes().size()));
-
-            Map<String, List<?>> features = nodeFeatures.stream()
-                .map(o -> (Map<?, ?>) o)
-                .collect(Collectors.toMap(m -> (String) m.get("node_id"), m -> (List<?>) m.get("features")));
-
-            Set<String> missing = features.entrySet()
-                .stream()
-                .filter(e -> e.getValue().contains(FeatureService.FEATURES_SUPPORTED.id()) == false)
-                .map(Map.Entry::getKey)
-                .collect(Collectors.toSet());
-            assertThat(missing + " out of " + features.keySet() + " does not have the required feature", missing, empty());
-        }
-    }
-}

server/src/internalClusterTest/java/org/elasticsearch/features/ClusterFeaturesIT.java

@@ -30,7 +30,6 @@ public class ClusterFeaturesIT extends ESIntegTestCase {
 
         FeatureService service = internalCluster().getCurrentMasterNodeInstance(FeatureService.class);
 
-        assertThat(service.getNodeFeatures(), hasKey(FeatureService.FEATURES_SUPPORTED.id()));
         assertThat(service.getNodeFeatures(), hasKey(FeatureService.TEST_FEATURES_ENABLED.id()));
 
         // check the nodes all have a feature in their cluster state (there should always be features_supported)
@@ -38,7 +37,7 @@ public class ClusterFeaturesIT extends ESIntegTestCase {
         var features = response.getState().clusterFeatures().nodeFeatures();
         Set<String> missing = features.entrySet()
             .stream()
-            .filter(e -> e.getValue().contains(FeatureService.FEATURES_SUPPORTED.id()) == false)
+            .filter(e -> e.getValue().contains(FeatureService.TEST_FEATURES_ENABLED.id()) == false)
             .map(Map.Entry::getKey)
             .collect(Collectors.toSet());
         assertThat(missing + " out of " + features.keySet() + " does not have the required feature", missing, empty());

server/src/main/java/org/elasticsearch/features/FeatureInfrastructureFeatures.java

@@ -13,18 +13,9 @@ import java.util.Set;
 
 /**
  * This class specifies features for the features functionality itself.
- * <p>
- * This adds a feature {@code features_supported} indicating that a node supports node features.
- * Nodes that do not support features won't have this feature in its feature set,
- * so this can be checked without needing to look at the node version.
  */
 public class FeatureInfrastructureFeatures implements FeatureSpecification {
 
-    @Override
-    public Set<NodeFeature> getFeatures() {
-        return Set.of(FeatureService.FEATURES_SUPPORTED);
-    }
-
     @Override
     public Set<NodeFeature> getTestFeatures() {
         return Set.of(FeatureService.TEST_FEATURES_ENABLED);

server/src/main/java/org/elasticsearch/features/FeatureService.java

@@ -26,10 +26,6 @@ import java.util.Map;
  */
 public class FeatureService {
 
-    /**
-     * A feature indicating that node features are supported.
-     */
-    public static final NodeFeature FEATURES_SUPPORTED = new NodeFeature("features_supported", true);
     public static final NodeFeature TEST_FEATURES_ENABLED = new NodeFeature("test_features_enabled");
 
     private static final Logger logger = LogManager.getLogger(FeatureService.class);

server/src/main/java/org/elasticsearch/features/FeatureSpecification.java

@@ -31,7 +31,7 @@ import java.util.Set;
  */
 public interface FeatureSpecification {
     /**
-     * Returns a set of regular features that this node supports.
+     * Returns a set of features that this node supports.
      */
     default Set<NodeFeature> getFeatures() {
         return Set.of();