assertj-core is only used in test code, so declare the dependency with test scope.

Author: Janne Kalliomäki

pom.xml

@@ -175,6 +175,7 @@
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
             <version>3.2.0</version>
+            <scope>test</scope>
         </dependency>
     </dependencies>