Problem using trailing delimiter in dissect

[Badger]

When I dissect a message like this:

input { generator { message => ';abc|def;' count => 1 } }
filter { dissect { mapping => { "message" => ";%{a}|%{b};" } } }
output { stdout { codec => rubydebug } }

I get the trailing semi-colon included in b, which, for me, is counter-intuitive. I know I can mutate/gsub the trailing character away, but it feels wrong. Is there a way to modify the dissect string to get this to set "b" => "def"?

       "message" => ";abc|def;",
      "sequence" => 0,
             "a" => "abc",
             "b" => "def;"

[Semyon]

Try adding silent/ skip field, at the end of message like so:
filter { dissect { mapping => { "message" => ";%{a}|%{b};%{}" } } }