gistfile1.scala

 override def packageOptions =
      manifestClassPath.map(cp => ManifestAttributes(
        (Attributes.Name.CLASS_PATH, cp),
        (IMPLEMENTATION_TITLE, "Backchat XMPP module"),
        (IMPLEMENTATION_URL, "http://backchat.im"),
        (IMPLEMENTATION_VENDOR, "Mojolly Ltd."),
        (IMPLEMENTATION_VERSION, version.toString)
      )).toList ::: getMainClass(false).map(MainClass(_)).toList

    def allArtifacts = {
      Path.fromFile(buildScalaInstance.libraryJar) +++
      (removeDupEntries(runClasspath filter ClasspathUtilities.isArchive) +++
      ((outputPath ##) / defaultJarName) +++
      mainDependencies.scalaJars +++
      mainDependencies.all +++
      descendents(configurationPath(Configurations.Compile) ##, "*.jar")) +++
      (bc_core.outputPath / bc_core.defaultJarName) +++
      (bc_client.outputPath / bc_client.defaultJarName)
    }

override def manifestClassPath = Some(allArtifacts.getFiles
        .filter(_.getName.endsWith(".jar"))
        .filter(!_.getName.contains("servlet_2.4"))
        .filter(!_.getName.contains("scala-library"))
        .map(_.getName)
        .mkString(" ") +
        " scala-library.jar" +
        " backchat-client_%s-%s".format(buildScalaVersion, version) +
        " backchat-core_%s-%s".format(buildScalaVersion, version) 
      )

Sorry, but could you please tell me which part of the above code is responsible for packaging dependent project A as a JAR and copying it to WEB-INF/lib of project B?