org.eclipse.m2e.discovery.oss/src/main/assembly/assembly.xml

<assembly>
  <id>catalog</id>
  <formats>
    <format>zip</format>
  </formats>
  <includeBaseDirectory>false</includeBaseDirectory>
  <fileSets>
    <fileSet>
      <directory>${project.build.directory}/p2repository</directory>
      <outputDirectory>/</outputDirectory>
    </fileSet>
    <fileSet>
      <directory>${project.build.directory}</directory>
      <includes>
        <include>${project.artifactId}-${project.version}.jar</include>
      </includes>
      <outputDirectory>/</outputDirectory>
    </fileSet>
  </fileSets>

</assembly>