Sharing variables with child maven projects - maven

Question

I have a parent pom.xml which builds a series of modules. As part of the parent pom.xml I read a configuration and put a number of variables into the build environment:
BUILD_DATE=2014/07/24 15\:37\:06
BUILD_NUMBER=78
VERSION=GGY1.6
I wish to place this information into the manifest jar file. I am doing this as follows:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<finalName>atf</finalName>
<archive>
<manifestEntries>
<Built-Date>${maven.build.timestamp}</Built-Date>
<Version>${VERSION}B${BUILD_NUMBER}</Version>
</manifestEntries>
</archive>
</configuration>
</plugin>
I am not sure which section of the pom.xml this should go into. I have put it in the build phase, and in some modules this works out ok, but in others it comes out in the manifest as:
Created-By: Apache Maven 3.0.5
Built-Date: 28/07/2014-16:00
Version: ${VERSION}B${BUILD_NUMBER}
Archiver-Version: Plexus Archiver
Is there a specific place in the pom.xml I need to put the maven-jar-plugin in order for it to pick up variables created by the parent?

Answer 1

I think the missing piece in the modules pom.xml files was this:
<plugin><groupId>org.codehaus.mojo</groupId>
<artifactId>properties-maven-plugin</artifactId>
</plugin>
Any module pom which had this piece added, populated the manifest correctly... along with the maven-jar-plugin snippet. It looks like both are needed in order to access the values set by the parent pom.xml