HBASE-19166 AsyncProtobufLogWriter persists ProtobufLogWriter as class name for backward compatibility

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/AsyncProtobufLogWriter.java

@@ -108,6 +108,15 @@ public class AsyncProtobufLogWriter extends AbstractProtobufLogWriter
     this.channelClass = channelClass;
   }
 
+  /*
+   * @return class name which is recognized by hbase-1.x to avoid ProtobufLogReader throwing error:
+   *   IOException: Got unknown writer class: AsyncProtobufLogWriter
+   */
+  @Override
+  protected String getWriterClassName() {
+    return "ProtobufLogWriter";
+  }
+
   @Override
   public void append(Entry entry) {
     int buffered = output.buffered();

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/SecureAsyncProtobufLogWriter.java

@@ -38,6 +38,14 @@ public class SecureAsyncProtobufLogWriter extends AsyncProtobufLogWriter {
     super(eventLoopGroup, channelClass);
   }
 
+  /*
+   * @return class name which is recognized by hbase-1.x to avoid ProtobufLogReader throwing error:
+   *   IOException: Got unknown writer class: SecureAsyncProtobufLogWriter
+   */
+  @Override
+  protected String getWriterClassName() {
+    return "SecureProtobufLogWriter";
+  }
   @Override
   protected WALHeader buildWALHeader(Configuration conf, WALHeader.Builder builder)
       throws IOException {