Gemfile

source 'https://rubygems.org'

# Specify your gem's dependencies in vtd-xml.gemspec
gemspec

# needed to build the gem but fails when it is part of the gems
gem "ruby-maven", '~> 3.1.1.0'

gistfile1.txt

vtd_xml $ rake build
vtd_xml 0.0.3 built to pkg/vtd_xml-0.0.3-java.gem.
[INFO] Scanning for projects...
/home/christian/projects/clones/vtd-xml-ruby/vtd_xml/.tesla.Mavenfile
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building I like VTD-XML so I use this instead of standard XML parsers 0.0.3
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- gem-maven-plugin:1.0.0-rc4:initialize (default-initialize) @ vtd_xml ---
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ vtd_xml ---
[INFO] Using 'utf-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /home/christian/projects/clones/vtd-xml-ruby/vtd_xml/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ vtd_xml ---
[INFO] No sources to compile
[INFO] 
[INFO] --- gem-maven-plugin:1.0.0-rc4:package (default-package) @ vtd_xml ---
[INFO] include dependencies? true
[INFO]  -- include -- com.ximpleware:vtd-xml:jar:2.11:compile
[WARNING] WARNING:  description and summary are identical
[INFO]   Successfully built RubyGem
[INFO]   Name: vtd_xml
[INFO]   Version: 0.0.3
[INFO]   File: vtd_xml-0.0.3-java.gem
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 13:13.981s
[INFO] Finished at: Mon Jan 20 11:53:56 GMT 2014
[INFO] Final Memory: 24M/286M
[INFO] ------------------------------------------------------------------------

Mavenfile

gemspec :include_jars => true

Mavenfile With Extra Debug

gemspec :include_jars => true
 
properties( 'jruby.plugins.version' => '1.0.0-SNAPSHOT',
            'tesla.dump.pom' => 'pom.xml' )
 
snapshot_repository 'https://oss.sonatype.org/content/repositories/snapshots', :id => 'oss'

output.log

arielvalentin@kimura:~/dev/repos/vtd-xml-ruby/vtd_xml 
git:ruby_maven_spike 
→ ls lib/
vtd_xml		vtd_xml.rb

arielvalentin@kimura:~/dev/repos/vtd-xml-ruby/vtd_xml 
git:ruby_maven_spike 
→ jruby -S rake clean build
[INFO] Scanning for projects...
/Users/arielvalentin/dev/repos/vtd-xml-ruby/vtd_xml/.tesla.Mavenfile
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building I like VTD-XML so I use this instead of standard XML parsers 0.0.3
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ vtd_xml ---
[INFO] Deleting /Users/arielvalentin/dev/repos/vtd-xml-ruby/vtd_xml/pkg
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.058s
[INFO] Finished at: Tue Jan 21 10:51:35 EST 2014
[INFO] Final Memory: 20M/310M
[INFO] ------------------------------------------------------------------------
vtd_xml 0.0.3 built to pkg/vtd_xml-0.0.3-java.gem.
[INFO] Scanning for projects...
/Users/arielvalentin/dev/repos/vtd-xml-ruby/vtd_xml/.tesla.Mavenfile
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building I like VTD-XML so I use this instead of standard XML parsers 0.0.3
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- gem-maven-plugin:1.0.0-rc4:initialize (default-initialize) @ vtd_xml ---
[INFO] Successfully installed bundler-1.5.2
[INFO] Successfully installed rake-10.1.1
[INFO] Successfully installed shoulda-context-1.1.6
[INFO] Successfully installed nokogiri-1.6.1-java
[INFO] Successfully installed mini_portile-0.5.2
[INFO] 5 gems installed
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ vtd_xml ---
[INFO] Using 'utf-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/arielvalentin/dev/repos/vtd-xml-ruby/vtd_xml/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ vtd_xml ---
[INFO] No sources to compile
[INFO] 
[INFO] --- gem-maven-plugin:1.0.0-rc4:package (default-package) @ vtd_xml ---
[INFO] include dependencies? true
[INFO]  -- include -- com.ximpleware:vtd-xml:jar:2.11:compile
[WARNING] WARNING:  description and summary are identical
[INFO]   Successfully built RubyGem
[INFO]   Name: vtd_xml
[INFO]   Version: 0.0.3
[INFO]   File: vtd_xml-0.0.3-java.gem
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 34.265s
[INFO] Finished at: Tue Jan 21 10:52:15 EST 2014
[INFO] Final Memory: 26M/327M
[INFO] ------------------------------------------------------------------------

arielvalentin@kimura:~/dev/repos/vtd-xml-ruby/vtd_xml 
git:ruby_maven_spike 
→ ls lib/
vtd_xml		vtd_xml.rb

arielvalentin@kimura:~/dev/repos/vtd-xml-ruby/vtd_xml 
git:ruby_maven_spike 
→ 

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <modelVersion>4.0.0</modelVersion>
  <groupId>rubygems</groupId>
  <artifactId>vtd_xml</artifactId>
  <version>0.0.3</version>
  <packaging>gem</packaging>
  <name>I like VTD-XML so I use this instead of standard XML parsers</name>
  <description>I like VTD-XML so I use this instead of standard XML parsers</description>
  <url>https://github.com/arielvalentin/vtd-xml-ruby</url>
  <properties>
    <jruby.plugins.version>1.0.0-rc4</jruby.plugins.version>
    <project.build.sourceEncoding>utf-8</project.build.sourceEncoding>
    <tesla.dump.pom>pom.xml</tesla.dump.pom>
  </properties>
  <dependencies>
    <dependency>
      <groupId>rubygems</groupId>
      <artifactId>bundler</artifactId>
      <version>[1.3,1.99999]</version>
      <type>gem</type>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>rubygems</groupId>
      <artifactId>rake</artifactId>
      <version>[0,)</version>
      <type>gem</type>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>rubygems</groupId>
      <artifactId>shoulda-context</artifactId>
      <version>[0,)</version>
      <type>gem</type>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>rubygems</groupId>
      <artifactId>nokogiri</artifactId>
      <version>[0,)</version>
      <type>gem</type>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.ximpleware</groupId>
      <artifactId>vtd-xml</artifactId>
      <version>2.11</version>
    </dependency>
  </dependencies>
  <repositories>
    <repository>
      <id>rubygems-releases</id>
      <url>http://rubygems-proxy.torquebox.org/releases</url>
    </repository>
  </repositories>
  <build>
    <extensions>
      <extension>
        <groupId>de.saumya.mojo</groupId>
        <artifactId>gem-extension</artifactId>
        <version>${jruby.plugins.version}</version>
      </extension>
    </extensions>
    <directory>${basedir}/pkg</directory>
    <plugins>
      <plugin>
        <groupId>de.saumya.mojo</groupId>
        <artifactId>gem-maven-plugin</artifactId>
        <version>${jruby.plugins.version}</version>
        <configuration>
          <gemspec>vtd_xml.gemspec</gemspec>
          <includeDependencies>true</includeDependencies>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

Using extra debug

git:ruby_maven_spike 
→ jruby -S rake clean build
[INFO] Scanning for projects...
/Users/arielvalentin/dev/repos/vtd-xml-ruby/vtd_xml/.tesla.Mavenfile
[WARNING] The POM for de.saumya.mojo:gem-extension:jar:1.0.0-SNAPSHOT is missing, no dependency information available
[ERROR] The build could not read 1 project -> [Help 1]
[ERROR]   
[ERROR]   The project rubygems:vtd_xml:0.0.3 (/Users/arielvalentin/dev/repos/vtd-xml-ruby/vtd_xml/.tesla.Mavenfile) has 2 errors
[ERROR]     Unresolveable build extension: Plugin de.saumya.mojo:gem-extension:1.0.0-SNAPSHOT or one of its dependencies could not be resolved: Could not find artifact de.saumya.mojo:gem-extension:jar:1.0.0-SNAPSHOT -> [Help 2]
[ERROR]     Unknown packaging: gem
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/ProjectBuildingException
[ERROR] [Help 2] http://cwiki.apache.org/confluence/display/MAVEN/PluginResolutionException
vtd_xml 0.0.3 built to pkg/vtd_xml-0.0.3-java.gem.
[INFO] Scanning for projects...
/Users/arielvalentin/dev/repos/vtd-xml-ruby/vtd_xml/.tesla.Mavenfile
[WARNING] The POM for de.saumya.mojo:gem-extension:jar:1.0.0-SNAPSHOT is missing, no dependency information available
[ERROR] The build could not read 1 project -> [Help 1]
[ERROR]   
[ERROR]   The project rubygems:vtd_xml:0.0.3 (/Users/arielvalentin/dev/repos/vtd-xml-ruby/vtd_xml/.tesla.Mavenfile) has 2 errors
[ERROR]     Unresolveable build extension: Plugin de.saumya.mojo:gem-extension:1.0.0-SNAPSHOT or one of its dependencies could not be resolved: Could not find artifact de.saumya.mojo:gem-extension:jar:1.0.0-SNAPSHOT -> [Help 2]
[ERROR]     Unknown packaging: gem
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/ProjectBuildingException
[ERROR] [Help 2] http://cwiki.apache.org/confluence/display/MAVEN/PluginResolutionException