remove NONE singleton in CompressorRegistry and remove static block init

Signed-off-by: Nicholas Walter Knize <nknize@apache.org>

libs/core/src/main/java/org/opensearch/core/compress/CompressorRegistry.java

@@ -31,23 +31,19 @@
  */
 @InternalApi
 public final class CompressorRegistry {
-    /** No compression singleton - we still register so users can specify NONE in the API*/
-    public static final Compressor NONE;
 
     // the backing registry map
-    private static final Map<String, Compressor> registeredCompressors;
+    private static final Map<String, Compressor> registeredCompressors = ServiceLoader.load(
+        CompressorProvider.class,
+        CompressorProvider.class.getClassLoader()
+    )
+        .stream()
+        .flatMap(p -> p.get().getCompressors().stream())
+        .collect(Collectors.toUnmodifiableMap(Map.Entry::getKey, Map.Entry::getValue));
 
     // no instance:
     private CompressorRegistry() {}
 
-    static {
-        registeredCompressors = ServiceLoader.load(CompressorProvider.class, CompressorProvider.class.getClassLoader())
-            .stream()
-            .flatMap(p -> p.get().getCompressors().stream())
-            .collect(Collectors.toUnmodifiableMap(Map.Entry::getKey, Map.Entry::getValue));
-        NONE = registeredCompressors.get(NoneCompressor.NAME);
-    }
-
     /**
      * Returns the default compressor
      */

server/src/main/java/org/opensearch/repositories/blobstore/BlobStoreRepository.java

@@ -402,7 +402,7 @@ protected BlobStoreRepository(
         cacheRepositoryData = CACHE_REPOSITORY_DATA.get(metadata.settings());
         bufferSize = Math.toIntExact(BUFFER_SIZE_SETTING.get(metadata.settings()).getBytes());
         maxShardBlobDeleteBatch = MAX_SNAPSHOT_SHARD_BLOB_DELETE_BATCH_SIZE.get(metadata.settings());
-        this.compressor = compress ? COMPRESSION_TYPE_SETTING.get(metadata.settings()) : CompressorRegistry.NONE;
+        this.compressor = compress ? COMPRESSION_TYPE_SETTING.get(metadata.settings()) : CompressorRegistry.none();
     }
 
     @Override
@@ -770,7 +770,7 @@ public BlobStore blobStore() {
      * @return true if compression is needed
      */
     protected final boolean isCompress() {
-        return compressor != CompressorRegistry.NONE;
+        return compressor != CompressorRegistry.none();
     }
 
     /**

server/src/test/java/org/opensearch/snapshots/BlobStoreFormatTests.java

@@ -119,7 +119,7 @@ public void testBlobStoreOperations() throws IOException {
         ChecksumBlobStoreFormat<BlobObj> checksumSMILE = new ChecksumBlobStoreFormat<>(BLOB_CODEC, "%s", BlobObj::fromXContent);
 
         // Write blobs in different formats
-        checksumSMILE.write(new BlobObj("checksum smile"), blobContainer, "check-smile", CompressorRegistry.NONE);
+        checksumSMILE.write(new BlobObj("checksum smile"), blobContainer, "check-smile", CompressorRegistry.none());
         checksumSMILE.write(
             new BlobObj("checksum smile compressed"),
             blobContainer,
@@ -142,7 +142,7 @@ public void testCompressionIsApplied() throws IOException {
         ChecksumBlobStoreFormat<BlobObj> checksumFormat = new ChecksumBlobStoreFormat<>(BLOB_CODEC, "%s", BlobObj::fromXContent);
         BlobObj blobObj = new BlobObj(veryRedundantText.toString());
         checksumFormat.write(blobObj, blobContainer, "blob-comp", CompressorRegistry.getCompressor(DeflateCompressor.NAME));
-        checksumFormat.write(blobObj, blobContainer, "blob-not-comp", CompressorRegistry.NONE);
+        checksumFormat.write(blobObj, blobContainer, "blob-not-comp", CompressorRegistry.none());
         Map<String, BlobMetadata> blobs = blobContainer.listBlobsByPrefix("blob-");
         assertEquals(blobs.size(), 2);
         assertThat(blobs.get("blob-not-comp").length(), greaterThan(blobs.get("blob-comp").length()));