Nifi DistributedMapCacheClient keySet unsupportedOperationException

Hi,

I'm trying to get all entries from a redis cache. When i try to remove, getbykey etc that work but when i call myCache.keySet, i face an issue with following exception: UnsupportedOperationEception on null.

I check it in git source repo and keySet method is implemented. May be there is a mistake in my deserializer ? I would like to know the point of view of Nifi community .

I'm currently stuck as i need to list all entries that are in redis in order to split them in other processor for a specific action in Nifi context.

BElow some piece of code :

- The deserializer

public static class StringDeserializer implements Deserializer<String>{

		@Override
		public String deserialize(byte[] input) throws DeserializationException, IOException {
			if (input == null || input.length == 0) {
                return null;
            }
            return input.toString();
		}
    }

 and piece of code of my custom processor code:

final DistributedMapCacheClient cache = context.getProperty(PROP_DISTRIBUTED_CACHE_SERVICE)
        		.asControllerService( DistributedMapCacheClient.class);
        
        // get all entry in cache
        try {
			Set<String> entries = cache.keySet(keyDeSerializer); // <== HERE CODE GENERATE ERROR
			logger.info("size ===> " + entries.size());
			entries.forEach(e->{
				logger.info( "********************* " + e.toString());
				
			});
			session.transfer(flowFile, REL_SUCCESS);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			session.transfer(flowFile, REL_FAILURE);
		}

 and to finish the stacktrace:

- failed to process session due to java.lang.UnsupportedOperationException;

- java.lang.UnsupportedOperationException: null
at org.apache.nifi.distributed.cache.client.DistributedMapCacheClient.keySet(DistributedMapCacheClient.java:221)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.nifi.controller.service.StandardControllerServiceInvocationHandler.invoke(StandardControllerServiceInvocationHandler.java:87)
at com.sun.proxy.$Proxy99.keySet(Unknown Source)
at com.**********.****.*****.processors.getRedisCache.FetchCacheWithoutInput.onTrigger(FetchCacheWithoutInput.java:121)
at org.apache.nifi.processor.AbstractProcessor.onTrigger(AbstractProcessor.java:27)
at org.apache.nifi.controller.StandardProcessorNode.onTrigger(StandardProcessorNode.java:1162)
at org.apache.nifi.controller.tasks.ConnectableTask.invoke(ConnectableTask.java:209)
at org.apache.nifi.controller.scheduling.TimerDrivenSchedulingAgent$1.run(TimerDrivenSchedulingAgent.java:117)
at org.apache.nifi.engine.FlowEngine$2.run(FlowEngine.java:110)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)