- Add 'register' method to null output so it actually works now.

lib/logstash/outputs/null.rb

@@ -6,6 +6,11 @@ require "logstash/namespace"
 class LogStash::Outputs::Null < LogStash::Outputs::Base
   config_name "null"
 
+  public
+  def register
+    # Nothing to do
+  end # def register
+
   public
   def receive(event)
     # Do nothing