One example of such a Map is in Spring Cloud stream. As things stand, there's no metadata for any of the properties on BindingProperties. I think it would be interesting to explore the possibility of providing metadata for those properties, perhaps using a wildcard for the key in the map:

spring.cloud.stream.bindings.*.content-type spring.cloud.stream.bindings.*.destination spring.cloud.stream.bindings.*.group … 

For this to be useful, we'd need a corresponding enhancement in each of the IDE plugins.