Initialize empty document subset bit set cache used for DLS

This commit initializes `DocumentSubsetBitsetCache` even if DLS
is disabled, previously it would throw null pointer when querying
usage stats. It is okay to initialize empty `DocumentSubsetBitsetCache`
so it does not fail when accessing usage stats.

Closes elastic#45147

x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/Security.java

@@ -361,10 +361,6 @@ Collection<Object> createComponents(Client client, ThreadPool threadPool, Cluste
         securityContext.set(new SecurityContext(settings, threadPool.getThreadContext()));
         components.add(securityContext.get());
 
-        if (XPackSettings.DLS_FLS_ENABLED.get(settings)) {
-            dlsBitsetCache.set(new DocumentSubsetBitsetCache(settings));
-        }
-
         // audit trail service construction
         final List<AuditTrail> auditTrails = XPackSettings.AUDIT_ENABLED.get(settings)
                 ? Collections.singletonList(new LoggingAuditTrail(settings, clusterService, threadPool))
@@ -408,6 +404,7 @@ Collection<Object> createComponents(Client client, ThreadPool threadPool, Cluste
         final NativePrivilegeStore privilegeStore = new NativePrivilegeStore(settings, client, securityIndex.get());
         components.add(privilegeStore);
 
+        dlsBitsetCache.set(new DocumentSubsetBitsetCache(settings));
         final FieldPermissionsCache fieldPermissionsCache = new FieldPermissionsCache(settings);
         final FileRolesStore fileRolesStore = new FileRolesStore(settings, env, resourceWatcherService, getLicenseState());
         final NativeRolesStore nativeRolesStore = new NativeRolesStore(settings, client, getLicenseState(), securityIndex.get());

x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/authz/store/CompositeRolesStore.java

@@ -106,17 +106,17 @@ public CompositeRolesStore(Settings settings, FileRolesStore fileRolesStore, Nat
                                ReservedRolesStore reservedRolesStore, NativePrivilegeStore privilegeStore,
                                List<BiConsumer<Set<String>, ActionListener<RoleRetrievalResult>>> rolesProviders,
                                ThreadContext threadContext, XPackLicenseState licenseState, FieldPermissionsCache fieldPermissionsCache,
-                               ApiKeyService apiKeyService, @Nullable DocumentSubsetBitsetCache dlsBitsetCache,
+                               ApiKeyService apiKeyService, DocumentSubsetBitsetCache dlsBitsetCache,
                                Consumer<Collection<RoleDescriptor>> effectiveRoleDescriptorsConsumer) {
-        this.fileRolesStore = fileRolesStore;
-        this.dlsBitsetCache = dlsBitsetCache;
+        this.fileRolesStore = Objects.requireNonNull(fileRolesStore);
+        this.dlsBitsetCache = Objects.requireNonNull(dlsBitsetCache);
         fileRolesStore.addListener(this::invalidate);
-        this.nativeRolesStore = nativeRolesStore;
-        this.privilegeStore = privilegeStore;
-        this.licenseState = licenseState;
-        this.fieldPermissionsCache = fieldPermissionsCache;
-        this.apiKeyService = apiKeyService;
-        this.effectiveRoleDescriptorsConsumer = effectiveRoleDescriptorsConsumer;
+        this.nativeRolesStore = Objects.requireNonNull(nativeRolesStore);
+        this.privilegeStore = Objects.requireNonNull(privilegeStore);
+        this.licenseState = Objects.requireNonNull(licenseState);
+        this.fieldPermissionsCache = Objects.requireNonNull(fieldPermissionsCache);
+        this.apiKeyService = Objects.requireNonNull(apiKeyService);
+        this.effectiveRoleDescriptorsConsumer = Objects.requireNonNull(effectiveRoleDescriptorsConsumer);
         CacheBuilder<RoleKey, Role> builder = CacheBuilder.builder();
         final int cacheSize = CACHE_SIZE_SETTING.get(settings);
         if (cacheSize >= 0) {