Add back missing plugin version

Author: atextor

core/esmf-aspect-model-serializer/pom.xml

@@ -87,6 +87,7 @@
          <plugin>
             <groupId>org.codehaus.mojo</groupId>
             <artifactId>properties-maven-plugin</artifactId>
+            <version>1.2.0</version>
             <executions>
                <execution>
                   <phase>generate-resources</phase>