KafkaConnector Exception while fetching from multiple kafka topics

./flink-connectors/flink-connector-kafka-0.9/src/main/java/org/apache/flink/streaming/connectors/kafka/internal/Kafka09Fetcher.java
 
It seems the List subscribedPartitionStates was being modified when runFetchLoop iterated the List.
This can happen if, e.g., FlinkKafkaConsumer runs the following code concurrently:
                kafkaFetcher.addDiscoveredPartitions(discoveredPartitions);
 

 java.util.ConcurrentModificationException
	at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:966)
	at java.util.LinkedList$ListItr.next(LinkedList.java:888)
	at org.apache.flink.streaming.connectors.kafka.internal.Kafka09Fetcher.runFetchLoop(Kafka09Fetcher.java:134)