GH-2968 DefaultErrorHandler#handleBatchAndReturnRemaining recovered i…

…nvalid

* address empty catch

spring-kafka/src/main/java/org/springframework/kafka/listener/FailedBatchProcessor.java

@@ -35,6 +35,7 @@
 
 import org.springframework.kafka.KafkaException;
 import org.springframework.kafka.KafkaException.Level;
+import org.springframework.kafka.support.KafkaUtils;
 import org.springframework.lang.Nullable;
 import org.springframework.util.backoff.BackOff;
 
@@ -246,13 +247,23 @@ private <K, V> ConsumerRecords<K, V> seekOrRecover(Exception thrownException, @N
 			return ConsumerRecords.empty();
 		}
 		else {
-			try {
-				if (getFailureTracker().recovered(remaining.get(0), thrownException, container,
-						consumer)) {
-					remaining.remove(0);
+			if (remaining.size() > 0) {
+				try {
+					if (getFailureTracker().recovered(remaining.get(0), thrownException, container,
+							consumer)) {
+						remaining.remove(0);
+					}
+				}
+				catch (Exception e) {
+					if (SeekUtils.isBackoffException(thrownException)) {
+						this.logger.debug(e, () -> KafkaUtils.format(remaining.get(0))
+								+ " included in remaining due to retry back off " + thrownException);
+					}
+					else {
+						this.logger.error(e, KafkaUtils.format(remaining.get(0))
+								+ " included in remaining due to " + thrownException);
+					}
 				}
-			}
-			catch (Exception e) {
 			}
 			if (remaining.isEmpty()) {
 				return ConsumerRecords.empty();