title: Write to GlobalStateStore on Kafka Streams
body: <p>I am trying to use addGlobalStore on a Kafka DSL where a need to store few values that I will need global access for all my threads/instances.</p>
  
  <p>My problem is that I need periodically to update these values inside my topology and make all running threads aware of the new values.</p>
  
  <p>I initialized the global store through <code>builder.addGlobalStore</code> and using the <code>init()</code> function of a Processor that was used as the last argument on this function, but I cannot find a way to update the values inside the global store.</p>
  
  <p>The next step on my Topology is a Transformer where I can get a hook through ```init()`` on the global Store and read the stored values but unfortunately I cannot updated them globally. I mean I can update the 
  local copy for the running thread but other threads/instances cannot see the change.</p>
  
  <p>I read somewhere that this cannot be done on Transformer, but even I use a Processor instead the issue remains</p>
  
  <p>So, Is there a way to update globalStateStore on a Kafka DSL topology,
  and if so how is this possible ? Or in order to use global store do I need to use the low level processor API ?</p>