What you are trying to do will not work when using Maven or Gradle. The reason is that when the artifact (jar most likely since you are using Spring Boot) is created, there will only be one application.properties file in the root.
I suggest you either change the name of the properties file on the support module and then configure Spring Boot to look for that file as well (take a look at this or this answer for pointers), or use some kind of merging task for your build tool (something like this perhaps)