title: How to modify content of default artifact with SBT
body: <p>I would like to know how can I modify the default artifact in order to have the following structure for my artifact published with SBT:</p>
  
  <pre><code>my_artifact.zip
              -config/default.conf
              -my_package.jar
  </code></pre>
  
  <p>It is actually quite straightforward case. I want my final artifact contain those two and to be able to change the type to zip. I have tried to access the default's artifact mappings as next without any results:</p>
  
  <pre><code>artifact in (Compile, publish) := {
    val previous: Artifact = (artifact in (Compile, publish)).value
    previous.withName("test_artifact"  + "." + previous.extension)
    previous.withType("zip")
    previous.withExtension("zip")
    previous
  }
  
  mappings in packagedArtifact in (Compile, packageBin) += {
    file(s"${baseDirectory.value.getPath}/src/main/config/current.conf") -&gt; "config/current.conf"
  }
  </code></pre>
  
  <p>Any suggestions how could I achieve this?</p>