SpringBoot Empty map from higher order property source does not override non-empty map

https://github.com/spring-projects/spring-boot/blob/bc3f028a1fcee9ebc3db013525a745e213c9675b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/MapBinder.java#L63

Comment From: mbhave

We are not going to change this behavior because this is consistent with how maps from various property sources get merged.