As reported in the last comments of this PR https://github.com/apache/flink/pull/3477#issuecomment-294306997 , currently the select()/flatSelect() functions receive the matched patterns as maps of the form Map<String, T>, where String is the name of the
pattern and T is the actual event.
With the introduction of quantifiers, we now may have multiple events for a given pattern (e.g. with oneOrMore()). To accommodate
this addition, this issue proposes to transform the output format of the matched patterns to Map<String, List<T>>.