Updating versions in multi-module Maven project - maven-3

Question

I am trying to release our multi-module Maven project and I can't figure out how to properly update the version numbers in our POMs.
The maven release plugin doesn't update versions in the parent POM dependencyManagement section - that seems to be a known bug.
I tried to use the versions plugin, but I have two issues with that:
the plugin only updates my toplevel POM; probably because the multi-module project POM is not the paremt POM of the modules's POMs
more significantly, how can I mimic the behavior of the release plugin to automatically compute the versions to set (e.g. 1.0.0) from the current version in the POMs (e.g. 1.0.0-SNAPSHOT)... without giong into perl scripting?
Any suggestion that doesn't involve scripting, and doesn't require me to declare dependency versions outside of dependencyManagement would be very appreciated!
Here are the 4 POMs (module POMs in their module subdirectory):
============ pom-parent.xml ==================
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.acme</groupId>
<artifactId>dummy-parent</artifactId>
<version>2.5</version>
<packaging>pom</packaging>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>com.acme</groupId>
<artifactId>module1</artifactId>
<version>1.0.0-SNAPSHOT</version>
</dependency>
</dependencies>
</dependencyManagement>
</project>
============= multi-module pom: pom.xml ================
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.acme</groupId>
<artifactId>dummy-parent</artifactId>
<relativePath>pom-parent.xml</relativePath>
<version>2.5</version>
</parent>
<groupId>com.acme</groupId>
<artifactId>multi-module</artifactId>
<version>1.0.0-SNAPSHOT</version>
<packaging>pom</packaging>
<modules>
<module>module1</module>
<module>module2</module>
</modules>
<scm>
<developerConnection>scm:svn:https://svnserver.fairisaac.com:8443/nowhere</developerConnection>
</scm>
</project>
============== module1 POM: module1/pom.xml ================
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.acme</groupId>
<artifactId>dummy-parent</artifactId>
<relativePath>../pom-parent.xml</relativePath>
<version>2.5</version>
</parent>
<groupId>com.acme</groupId>
<artifactId>module1</artifactId>
<version>1.0.0-SNAPSHOT</version>
<packaging>jar</packaging>
</project>
============= Module 2 POM: module2/pom.xml =============
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.acme</groupId>
<artifactId>dummy-parent</artifactId>
<relativePath>../pom-parent.xml</relativePath>
<version>2.5</version>
</parent>
<groupId>com.acme</groupId>
<artifactId>module2</artifactId>
<version>1.0.0-SNAPSHOT</version>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>com.acme</groupId>
<artifactId>module1</artifactId>
</dependency>
</dependencies>
</project>
========= Edit ==============
... and it gets better, if I replace the explicit version in the dependencyManagement section with
<version>${project.version}</version>
... maven 3.0.4 fails with an NPE:
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 4.478s
[INFO] Finished at: Fri Apr 12 12:09:08 CEST 2013
[INFO] Final Memory: 9M/120M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-release-plugin:2.0:prepare (default-cli) on project multi-
module: Execution default-cli of goal org.apache.maven.plugins:maven-release-plugin:2.0:prepare failed. NullPointerExcep
tion -> [Help 1]

Answer 1

This is not a bug, the first pom.xml you showed is outside your multi-module project. The maven-release-plugin will consider it an external dependency, thus it won't change the version.
But there is a flaw in your design, you have to move the
<dependencyManagement>
<dependencies>
<dependency>
<groupId>com.acme</groupId>
<artifactId>module1</artifactId>
<version>1.0.0-SNAPSHOT</version>
</dependency>
</dependencies>
</dependencyManagement>
to your multi-module pom.
I'm assuming your idea is to declare the module version in one place and share it among all modules. So, the module version goes into the multi-module pom dependencyManagement.
Usually external poms like this are used to put company information, repository paths, things like this, and they are shared by many different projects.