document mass reformatting

Author: mr-c

.git-blame-ignore-revs

@@ -0,0 +1,2 @@
+# reformatting using fmt-maven-plugin / google-java-format which follows Google's code styleguide.
+d5e1f5bfb85256e8a69441aaea62c01f398f43f9

CONTRIBUTING.md

@@ -75,6 +75,12 @@ application built with [Spring Boot](https://projects.spring.io/spring-boot/).
 Packaging is done by feature and all Spring configuration is 
 Java annotation based.
 
+The code is auto-formatted using [fmt-maven-plugin](https://github.com/spotify/fmt-maven-plugin)
+using [google-java-format](https://github.com/google/google-java-format)
+which follows [Google's code styleguide](https://google.github.io/styleguide/javaguide.html).
+
+You can run `mvn process-sources` to manually format the code.
+
 Templates for the view use [Thymeleaf](http://www.thymeleaf.org/), 
 which allows them to be displayed in browsers as static prototypes.