Add missing Java docs and minor clean up

Signed-off-by: Bukhtawar Khan <[email protected]>

server/src/main/java/org/opensearch/index/translog/InternalTranslogManager.java

@@ -142,8 +142,7 @@ public void recoverFromTranslog(TranslogRecoveryRunner translogRecoveryRunner, l
         }
     }
 
-    private void recoverFromTranslogInternal(TranslogRecoveryRunner translogRecoveryRunner, long localCheckpoint, long recoverUpToSeqNo)
-        throws IOException {
+    private void recoverFromTranslogInternal(TranslogRecoveryRunner translogRecoveryRunner, long localCheckpoint, long recoverUpToSeqNo) {
         final int opsRecovered;
         if (localCheckpoint < recoverUpToSeqNo) {
             try (Translog.Snapshot snapshot = translog.newSnapshot(localCheckpoint + 1, recoverUpToSeqNo)) {

server/src/main/java/org/opensearch/index/translog/NoOpTranslogManager.java

@@ -14,6 +14,9 @@
 import java.io.IOException;
 import java.util.stream.Stream;
 
+/**
+ * The no-op implementation of {@link TranslogManager} that doesn't perform any action
+ */
 public class NoOpTranslogManager implements TranslogManager {
 
     private final Translog.Snapshot emptyTranslogSnapshot;

server/src/main/java/org/opensearch/index/translog/TranslogManager.java

@@ -43,13 +43,13 @@ public interface TranslogManager {
 
     /**
      * Syncs translog to disk
-     * @throws IOException
+     * @throws IOException the exception while performing the sync operation
      */
     void syncTranslog() throws IOException;
 
     /**
      * Translog operation stats
-     * @return
+     * @return the translog stats
      */
     TranslogStats getTranslogStats();
 
@@ -94,8 +94,8 @@ public interface TranslogManager {
 
     /**
      * Returns the instance of the translog with a precondition
-     * @param ensureOpen
-     * @return
+     * @param ensureOpen check if the engine is open
+     * @return the translog instance
      */
     Translog getTranslog(boolean ensureOpen);
 

server/src/main/java/org/opensearch/index/translog/TranslogRecoveryRunner.java

@@ -10,6 +10,9 @@
 
 import java.io.IOException;
 
+/**
+ * The interface that defines how translog operations will get replayed from a {@link Translog.Snapshot}
+ */
 @FunctionalInterface
 public interface TranslogRecoveryRunner {
     int run(Translog.Snapshot snapshot) throws IOException;

server/src/main/java/org/opensearch/index/translog/listener/package-info.java

@@ -0,0 +1,11 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+/**
+ * Provides mechanism to listen into translog operations
+ */
+package org.opensearch.index.translog.listener;