NiFi v1.7.1 : java.lang.reflect.InvocationTargetException:null Error for custom processor

I have created a Custom processor to use AWS Encryption SDK as a separate processor in NiFi version 1.7.1

I have implemented Abstract class with required Properties and createClient functions and processor main class with getSupportedPropertyDescriptors, onTrigger funtions.

But when I am trying to run the processor it gives below error:-

2018-08-15 23:15:39,732 ERROR [Timer-Driven Process Thread-5] o.a.n.p.a.encryption.EncryptorProcessor EncryptorProcessor[id=3eaf70a8-0165-1000-a4d1-6cfa42125382] Failed to properly initialize Processor. If still scheduled to run, NiFi will attempt to initialize and run the Processor again after the 'Administrative Yield Duration' has elapsed. Failure is due to java.lang.reflect.InvocationTargetException: java.lang.reflect.InvocationTargetException
java.lang.reflect.InvocationTargetException: null
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.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:142)
at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:130)
at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:75)
at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotation(ReflectionUtils.java:52)
at org.apache.nifi.controller.StandardProcessorNode.lambda$initiateStart$4(StandardProcessorNode.java:1499)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
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)
Caused by: java.lang.NullPointerException: null
at org.apache.nifi.processors.aws.AbstractAWSProcessor.createConfiguration(AbstractAWSProcessor.java:221)
at org.apache.nifi.processors.aws.AbstractAWSProcessor.onScheduled(AbstractAWSProcessor.java:268)
at org.apache.nifi.processors.aws.AbstractAWSCredentialsProviderProcessor.onScheduled(AbstractAWSCredentialsProviderProcessor.java:65)
... 15 common frames omitted

Any help would be appreciated!