This change adds a grok_pattern field to the GET categories API
output in ML. It's calculated using the regex and examples in the
categorization result, and applying a list of candidate Grok
patterns to the bits in between the tokens that are considered to
define the category.
This can currently be considered a prototype, as the Grok patterns
it produces are not optimal. However, enough people have said it
would be useful for it to be worthwhile exposing it as experimental
functionality for interested parties to try out.
The overall NOTICE file for the ML X-Pack module should
include the notices from the 3rd party C++ components as
well as the 3rd party Java components.
David Roberts
Ryan Ernst