Maven doesn't attach non-archived files with mavenAssemblyPlugin - maven

Question

I have some list of files (.jil).
I'd like to attach them to the build using maven-assembly-plugin.
I have no difficulty deploying these with the "zip"
format.
However, the "dir" format throw an exception:
[WARNING] Assembly file: C:\Branches\project-branch\target\project\output\directory is not a regular file (it may be a directory). It cannot be attached to the project build for installation or deployment.
pom file:
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.2.1</version>
<executions>
<execution>
<id>make-devq</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<descriptors>
<descriptor>
${basedir}/environments/dev/assembly/descriptor.xml
</descriptor>
</descriptors>
<finalName>project</finalName>
<appendAssemblyId>true</appendAssemblyId>
<workDirectory>
${project.build.directory}/${project.artifactId}/work/project
</workDirectory>
<outputDirectory>
${project.build.directory}/${project.artifactId}/output
</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
assembly descriptor:
<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2 http://maven.apache.org/xsd/assembly-1.1.2.xsd">
<id>project-id</id>
<formats>
<format>dir</format>
</formats>
<includeBaseDirectory>false</includeBaseDirectory>
<fileSets>
<fileSet>
<directory>${basedir}/environments/dev/jils/</directory>
<outputDirectory>/</outputDirectory>
<includes>
<include>*.jil</include>
</includes>
</fileSet>
</fileSets>
</assembly>

Answer 1

To add separate files you should use the build-helper-maven-plugin which offers such options to you.
<project>
...
<build>
<plugins>
<plugin>
<!-- add configuration for antrun or another plugin here -->
</plugin>
...
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<version>1.8</version>
<executions>
<execution>
<id>attach-artifacts</id>
<phase>package</phase>
<goals>
<goal>attach-artifact</goal>
</goals>
<configuration>
<artifacts>
<artifact>
<file>some file</file>
<type>extension of your file </type>
<classifier>optional</classifier>
</artifact>
...
</artifacts>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
With the dir format you can't attach these files to your project.
BTW: The current up-to-date version of maven-assembly-plugin is 2.4.

Answer 2

According to Maven doc, the accepted formats are:
dir - Creates a directory zip
Creates a ZIP file format tar
Creates a TAR format tar.gz
Creates a gzip'd TAR format tar.bz2
Creates a bzip'd TAR format