Going back to maven-compiler-plugin 2.0.2 in bootstrap,

cause maven-compiler-plugin 3.1 is already defined in group-6

core-it-suite/src/test/resources/bootstrap/pom.xml

@@ -55,7 +55,7 @@ under the License.
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.1</version>
+        <version>2.0.2</version>
       </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>