mavengem protocol converts a rubygems repository on the fly to a maven repository and the mavengem wagon uses it to provide gem artifacts to maven POMs
'org.torquebox.mojo:mavengem-protocol:0.2.0'
<dependency> <groupId>org.torquebox.mojo</groupId> <artifactId>mavengem-protocol</artifactId> <version>0.2.0</version> </dependency>
<dependency org="org.torquebox.mojo" name="mavengem-protocol" rev="0.2.0"/>
"org.torquebox.mojo", "mavengem-protocol", "0.2.0"