Spring boot could not resolve placeholder in string

Question

I am running spring-boot on an embedded tomcat server through maven with mvn clean install spring-boot:run. But every time I run it I get this error:

Answer 1

Fixed by adding these lines to the pom under the section

     src/main/resources
     true
     
          **/*.properties
     

What I don't fully understand is the need for doing this.

a) I can run this on an external app server without having to add this line and the app reads application.properties just fine.

b) I can run the app as a standalone java application in eclipse (i.e., without having to build the app through maven) and it reads application.properties just fine

c) isn't spring-boot supposed to read it by default regardless? (as shown by the two cases above?)

Thanks everyone for their help. hopefully this will help others.