Github user ottobackwards commented on the issue:
https://github.com/apache/metron/pull/1207
We have an overall deficiency here I believe. The Slot management is a oft
forgotten and manual task, for adding new parsers from the ui etc, you ( I
believe ) still have to remember to have already added a slot before starting
your parser topology for example. We may want to consider an overall
underlying approach to this that is usable where we fall short.---
