Addressed Comments

src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/GetRecordsCache.java

@@ -16,7 +16,6 @@
 package com.amazonaws.services.kinesis.clientlibrary.lib.worker;
 
 import com.amazonaws.services.kinesis.clientlibrary.types.ProcessRecordsInput;
-import com.amazonaws.services.kinesis.metrics.interfaces.IMetricsScope;
 
 /**
  * This class is used as a cache for Prefetching data from Kinesis.

src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/PrefetchGetRecordsCache.java

@@ -29,6 +29,7 @@ import com.amazonaws.services.kinesis.model.GetRecordsResult;
 
 import lombok.NonNull;
 import lombok.extern.apachecommons.CommonsLog;
+import org.apache.commons.lang.Validate;
 
 /**
  * This is the prefetch caching class, this class spins up a thread if prefetching is enabled. That thread fetches the
@@ -91,6 +92,7 @@ public class PrefetchGetRecordsCache implements GetRecordsCache {
         this.metricsFactory = new ThreadSafeMetricsDelegatingFactory(metricsFactory);
         this.idleMillisBetweenCalls = idleMillisBetweenCalls;
         this.defaultGetRecordsCacheDaemon = new DefaultGetRecordsCacheDaemon();
+        Validate.notEmpty(operation, "Operation cannot be empty");
         this.operation = operation;
     }
 

src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/RecordsFetcherFactory.java

@@ -26,7 +26,7 @@ public interface RecordsFetcherFactory {
      * @param getRecordsRetrievalStrategy GetRecordsRetrievalStrategy to be used with the GetRecordsCache
      * @param shardId ShardId of the shard that the fetcher will retrieve records for
      * @param metricsFactory MetricsFactory used to create metricScope
-     * @param operation operation used to set metricScope
+     * @param operation operation name used to emit metrics
      *                
      * @return GetRecordsCache used to get records from Kinesis.
      */