Activate flatten maven plugin

.gitignore

@@ -21,3 +21,4 @@ hs_err_pid*
 # intelliJ
 .idea/
 *.iml
+.flattened-pom.xml

pom.xml

@@ -191,6 +191,32 @@
     <build>
         <pluginManagement>
             <plugins>
+                <plugin>
+                    <groupId>org.codehaus.mojo</groupId>
+                    <artifactId>flatten-maven-plugin</artifactId>
+                    <version>1.2.7</version>
+                    <configuration>
+                        <updatePomFile>true</updatePomFile>
+                        <flattenMode>resolveCiFriendliesOnly</flattenMode>
+                    </configuration>
+                    <executions>
+                        <execution>
+                            <id>flatten</id>
+                            <goals>
+                                <goal>flatten</goal>
+                            </goals>
+                            <phase>process-resources</phase>
+                        </execution>
+                        <execution>
+                            <id>flatten.clean</id>
+                            <goals>
+                                <goal>clean</goal>
+                            </goals>
+                            <phase>clean</phase>
+                        </execution>
+                    </executions>
+                </plugin>
+
                 <plugin>
                     <groupId>com.helger.maven</groupId>
                     <artifactId>ph-javacc-maven-plugin</artifactId>
@@ -267,6 +293,10 @@
             </plugins>
         </pluginManagement>
         <plugins>
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>flatten-maven-plugin</artifactId>
+            </plugin>
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>build-helper-maven-plugin</artifactId>