Don't try to convert it, just create a new Xtend project packaged for maven.
(You can import it into eclipse, import...existing maven project) then include your sources in src/main/java, and your dependencies in the pom.xml
From the documentation, here is the CLI to create the project: :
mvn archetype:generate -DarchetypeGroupId=org.eclipse.xtend -DarchetypeArtifactId=xtend-archetype
Here is an (old) example of a project i have generated, with an assermbly packaging for distribution
https://github.com/pdemanget/examples/tree/master/xtend/message-send
Documentation
https://www.eclipse.org/xtend/download.html
Basicaly it uses the Xtend compiler in a maven plugin, by adding this to the pom.xml
<dependency>
<groupId>org.eclipse.xtend</groupId>
<artifactId>org.eclipse.xtend.lib</artifactId>
<version>2.13.0</version>
</dependency>
and the Xtend compiler plugin:
<plugin>
<groupId>org.eclipse.xtend</groupId>
<artifactId>xtend-maven-plugin</artifactId>
<version>2.13.0</version>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>testCompile</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/xtend-gen/main</outputDirectory>
<testOutputDirectory>${project.build.directory}/xtend-gen/test</testOutputDirectory>
</configuration>
</execution>
</executions>