I humbly submit my first plugin, which is also my first "project" in Ruby. Please go easy on me 
I wrote this plugin because our data model includes a bitfield and there have been no other options to do this within the existing ELK pipeline (as far as I know). When configured with a map of flags to bit values, this will convert an integer representing the source bitfield to a map of flag and boolean value pairs.
Example
@trans from config:
-- { "trans1" =>1, "trans2" =>2, "trans3" =>4, "trans4" =>8, "trans5" =>12, "trans6" => 16, "trans7" =>32, "trans8" =>64, "trans9" =>128 }
@source integer:
-- { "flag_source": 191 }
this should translate to
-- event[@target] = {"trans7"=>true, "trans8"=>false, "trans9"=>true, "trans1"=>true, "trans2"=>true, "trans3"=>true, "trans4"=>true, "trans5"=>true, "trans6"=>true}
Please let me know if you find this useful, or if you find it broken, or if you have any other comments or questions. I can frequently be found in the freenode IRC channels going by the nick 'edx'.
-Ed