Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/4612#discussion_r156956540
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/Types.scala
---
@@ -107,7 +180,9 @@ object Types {
* @param keyType type of the keys of the map e.g. Types.STRING
--- End diff --
Add information about nullability of Map and entries?---
