Smack 4.1.2 - Unable to parse Result IQ of XEP-0191

I have implemented XEP-0191 (blocking Commands) using following Code

https://github.com/kontalk/client-common-java/blob/master/src/main/java/org/kont alk/client/BlockingCommand.java

The Problem, I am facing is 'On requesting a BlockList' using stanza

<iqtype='get'id='blocklist1'>
  <blocklistxmlns='urn:xmpp:blocking'/>
</iq>

I am able to see the XMPP Result IQ (with SmackConfiguration.DEBUG_ENABLED = TRUE)

RECV (0): <iq from='123xxx@xxx.com' to='123xxx@xxx.com/res' id='-9' type='result'><blocklist xmlns='urn:xmpp:blocking'><item jid='92345607xxx@xxx.com/res'/><item jid='923445xxxx@xxx.com'/></blocklist></iq>

But my IQ Listener is ignoring the above Packet.

Although I have included the following lines as well

ProviderManager.addIQProvider(BlockingCommand.BLOCK, BlockingCommand.NAMESPACE, new BlockingCommand.Provider());
ProviderManager.addIQProvider(BlockingCommand.UNBLOCK, BlockingCommand.NAMESPACE, new BlockingCommand.Provider());
ProviderManager.addIQProvider(BlockingCommand.BLOCKLIST, BlockingCommand.NAMESPACE, new BlockingCommand.Provider());
ProviderManager.addIQProvider(BlockingCommand.UNALLOW, BlockingCommand.NAMESPACE, new BlockingCommand.Provider());