Adding initialized boolean to record work state

Due to the long startup time of workers it's helpful to find out if they are ready for work.

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

@@ -94,6 +94,8 @@ public class Worker implements Runnable {
     private volatile long shutdownStartTimeMillis;
     private volatile boolean shutdownComplete = false;
     
+    private volatile boolean initialized = false;
+
     // Holds consumers for shards the worker is currently tracking. Key is shard
     // info, value is ShardConsumer.
     private ConcurrentMap<ShardInfo, ShardConsumer> shardInfoShardConsumerMap =
@@ -457,6 +459,7 @@ public class Worker implements Runnable {
         if (!isDone) {
             throw new RuntimeException(lastException);
         }
+        initialized = true;
     }
 
     /**
@@ -580,6 +583,10 @@ public class Worker implements Runnable {
         return shutdownComplete;
     }
     
+    public boolean isInitialized() {
+        return initialized;
+    }
+
     ConcurrentMap<ShardInfo, ShardConsumer> getShardInfoShardConsumerMap() {
         return shardInfoShardConsumerMap;
     }
@@ -630,6 +637,7 @@ public class Worker implements Runnable {
         if (metricsFactory instanceof WorkerCWMetricsFactory) {
             ((CWMetricsFactory) metricsFactory).shutdown();
         }        
+        initialized = false;
         shutdownComplete = true;        
     }