[#40366] Silence some lint warnings in server project (#48927)

Part of #40366. Silence a number of lint warnings in the :server
project, which arise when re-enabling suppressed warnings in
server/build.gradle.

Author: pugnascotia

server/src/main/java/org/elasticsearch/cluster/ClusterState.java

@@ -216,6 +216,7 @@ public ImmutableOpenMap<String, Custom> getCustoms() {
         return this.customs;
     }
 
+    @SuppressWarnings("unchecked")
     public <T extends Custom> T custom(String type) {
         return (T) customs.get(type);
     }
@@ -366,6 +367,7 @@ public String toString() {
     }
 
     @Override
+    @SuppressWarnings("unchecked")
     public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
         EnumSet<Metric> metrics = Metric.parseString(params.param("metric", "_all"), true);
 

server/src/main/java/org/elasticsearch/cluster/metadata/MappingMetaData.java

@@ -118,6 +118,7 @@ public CompressedXContent source() {
     /**
      * Converts the serialized compressed form of the mappings into a parsed map.
      */
+    @SuppressWarnings("unchecked")
     public Map<String, Object> sourceAsMap() throws ElasticsearchParseException {
         Map<String, Object> mapping = XContentHelper.convertToMap(source.compressedReference(), true).v2();
         if (mapping.size() == 1 && mapping.containsKey(type())) {

server/src/main/java/org/elasticsearch/common/cache/Cache.java

@@ -336,7 +336,8 @@ void eviction() {
     }
 
     public static final int NUMBER_OF_SEGMENTS = 256;
-    @SuppressWarnings("unchecked") private final CacheSegment<K, V>[] segments = new CacheSegment[NUMBER_OF_SEGMENTS];
+    @SuppressWarnings({"unchecked", "rawtypes"})
+    private final CacheSegment<K, V>[] segments = new CacheSegment[NUMBER_OF_SEGMENTS];
 
     {
         for (int i = 0; i < segments.length; i++) {

server/src/main/java/org/elasticsearch/common/document/DocumentField.java

@@ -73,11 +73,12 @@ public String getName() {
     /**
      * The first value of the hit.
      */
+    @SuppressWarnings("unchecked")
     public <V> V getValue() {
         if (values == null || values.isEmpty()) {
             return null;
         }
-        return (V)values.get(0);
+        return (V) values.get(0);
     }
 
     /**

server/src/main/java/org/elasticsearch/common/io/stream/NamedWriteableRegistry.java

@@ -63,6 +63,7 @@ public <T extends NamedWriteable> Entry(Class<T> categoryClass, String name, Wri
     /**
      * Constructs a new registry from the given entries.
      */
+    @SuppressWarnings("rawtypes")
     public NamedWriteableRegistry(List<Entry> entries) {
         if (entries.isEmpty()) {
             registry = Collections.emptyMap();

server/src/main/java/org/elasticsearch/common/io/stream/StreamInput.java

@@ -748,13 +748,12 @@ public final Instant readOptionalInstant() throws IOException {
         return present ? readInstant() : null;
     }
 
-    @SuppressWarnings("unchecked")
-    private List readArrayList() throws IOException {
+    private List<Object> readArrayList() throws IOException {
         int size = readArraySize();
         if (size == 0) {
             return Collections.emptyList();
         }
-        List list = new ArrayList(size);
+        List<Object> list = new ArrayList<>(size);
         for (int i = 0; i < size; i++) {
             list.add(readGenericValue());
         }
@@ -790,7 +789,7 @@ private Map readLinkedHashMap() throws IOException {
         if (size9 == 0) {
             return Collections.emptyMap();
         }
-        Map map9 = new LinkedHashMap(size9);
+        Map<String, Object> map9 = new LinkedHashMap<>(size9);
         for (int i = 0; i < size9; i++) {
             map9.put(readString(), readGenericValue());
         }
@@ -802,7 +801,7 @@ private Map readHashMap() throws IOException {
         if (size10 == 0) {
             return Collections.emptyMap();
         }
-        Map map10 = new HashMap(size10);
+        Map<String, Object> map10 = new HashMap<>(size10);
         for (int i = 0; i < size10; i++) {
             map10.put(readString(), readGenericValue());
         }
@@ -985,6 +984,7 @@ public <T extends Writeable> T readOptionalWriteable(Writeable.Reader<T> reader)
         }
     }
 
+    @SuppressWarnings("unchecked")
     public <T extends Exception> T readException() throws IOException {
         if (readBoolean()) {
             int key = readVInt();

server/src/main/java/org/elasticsearch/common/lucene/Lucene.java

@@ -264,7 +264,7 @@ public static void cleanLuceneIndex(Directory directory) throws IOException {
     }
 
     public static void checkSegmentInfoIntegrity(final Directory directory) throws IOException {
-        new SegmentInfos.FindSegmentsFile(directory) {
+        new SegmentInfos.FindSegmentsFile<>(directory) {
 
             @Override
             protected Object doBody(String segmentFileName) throws IOException {
@@ -345,7 +345,7 @@ public static TopDocsAndMaxScore readTopDocs(StreamInput in) throws IOException
     }
 
     public static FieldDoc readFieldDoc(StreamInput in) throws IOException {
-        Comparable[] cFields = new Comparable[in.readVInt()];
+        Comparable<?>[] cFields = new Comparable<?>[in.readVInt()];
         for (int j = 0; j < cFields.length; j++) {
             byte type = in.readByte();
             if (type == 0) {
@@ -375,7 +375,7 @@ public static FieldDoc readFieldDoc(StreamInput in) throws IOException {
         return new FieldDoc(in.readVInt(), in.readFloat(), cFields);
     }
 
-    public static Comparable readSortValue(StreamInput in) throws IOException {
+    public static Comparable<?> readSortValue(StreamInput in) throws IOException {
         byte type = in.readByte();
         if (type == 0) {
             return null;
@@ -484,7 +484,7 @@ public static void writeSortValue(StreamOutput out, Object field) throws IOExcep
         if (field == null) {
             out.writeByte((byte) 0);
         } else {
-            Class type = field.getClass();
+            Class<?> type = field.getClass();
             if (type == String.class) {
                 out.writeByte((byte) 1);
                 out.writeString((String) field);

server/src/main/java/org/elasticsearch/common/settings/AbstractScopedSettings.java

@@ -302,6 +302,7 @@ public void apply(Map<String, Tuple<A, B>> values, Settings current, Settings pr
      * Note: Only settings registered in {@link SettingsModule} can be changed dynamically.
      * </p>
      */
+    @SuppressWarnings("rawtypes")
     public synchronized void addAffixGroupUpdateConsumer(List<Setting.AffixSetting<?>> settings, BiConsumer<String, Settings> consumer) {
         List<SettingUpdater> affixUpdaters = new ArrayList<>(settings.size());
         for (Setting.AffixSetting<?> setting : settings) {
@@ -503,7 +504,7 @@ void validate(final String key, final Settings settings, final boolean validateD
      */
     void validate(
             final String key, final Settings settings, final boolean validateDependencies, final boolean validateInternalOrPrivateIndex) {
-        Setting setting = getRaw(key);
+        Setting<?> setting = getRaw(key);
         if (setting == null) {
             LevenshteinDistance ld = new LevenshteinDistance();
             List<Tuple<Float, String>> scoredKeys = new ArrayList<>();

server/src/main/java/org/elasticsearch/common/settings/IndexScopedSettings.java

@@ -194,7 +194,7 @@ public IndexScopedSettings copy(Settings settings, IndexMetaData metaData) {
     }
 
     @Override
-    protected void validateSettingKey(Setting setting) {
+    protected void validateSettingKey(Setting<?> setting) {
         if (setting.getKey().startsWith("index.") == false) {
             throw new IllegalArgumentException("illegal settings key: [" + setting.getKey() + "] must start with [index.]");
         }

server/src/main/java/org/elasticsearch/common/util/CollectionUtils.java

@@ -152,6 +152,7 @@ public static void ensureNoSelfReferences(Object value, String messageHint) {
         }
     }
 
+    @SuppressWarnings("unchecked")
     private static Iterable<?> convert(Object value) {
         if (value == null) {
             return null;
@@ -267,12 +268,13 @@ public static int sortAndDedup(final BytesRefArray bytes, final int[] indices) {
 
     }
 
+    @SuppressWarnings("unchecked")
     public static <E> ArrayList<E> iterableAsArrayList(Iterable<? extends E> elements) {
         if (elements == null) {
             throw new NullPointerException("elements");
         }
         if (elements instanceof Collection) {
-            return new ArrayList<>((Collection)elements);
+            return new ArrayList<>((Collection) elements);
         } else {
             ArrayList<E> list = new ArrayList<>();
             for (E element : elements) {
@@ -282,13 +284,17 @@ public static <E> ArrayList<E> iterableAsArrayList(Iterable<? extends E> element
         }
     }
 
+    @SafeVarargs
+    @SuppressWarnings("varargs")
     public static <E> ArrayList<E> arrayAsArrayList(E... elements) {
         if (elements == null) {
             throw new NullPointerException("elements");
         }
         return new ArrayList<>(Arrays.asList(elements));
     }
 
+    @SafeVarargs
+    @SuppressWarnings("varargs")
     public static <E> ArrayList<E> asArrayList(E first, E... other) {
         if (other == null) {
             throw new NullPointerException("other");
@@ -299,6 +305,8 @@ public static <E> ArrayList<E> asArrayList(E first, E... other) {
         return list;
     }
 
+    @SafeVarargs
+    @SuppressWarnings("varargs")
     public static<E> ArrayList<E> asArrayList(E first, E second, E... other) {
         if (other == null) {
             throw new NullPointerException("other");