build: add maven flatten plugin

Author: philipsens

pom.xml

@@ -165,6 +165,31 @@
 				<artifactId>maven-site-plugin</artifactId>
 				<version>3.12.1</version>
 			</plugin>
+			<plugin>
+				<groupId>org.codehaus.mojo</groupId>
+				<artifactId>flatten-maven-plugin</artifactId>
+				<version>1.6.0</version>
+				<configuration>
+					<updatePomFile>true</updatePomFile>
+					<flattenMode>resolveCiFriendliesOnly</flattenMode>
+				</configuration>
+				<executions>
+					<execution>
+						<id>flatten</id>
+						<phase>initialize</phase>
+						<goals>
+							<goal>flatten</goal>
+						</goals>
+					</execution>
+					<execution>
+						<id>clean</id>
+						<phase>clean</phase>
+						<goals>
+							<goal>clean</goal>
+						</goals>
+					</execution>
+				</executions>
+			</plugin>
 		</plugins>
 	</build>