in packaging/src/main/scala/org/jetbrains/sbtidea/packaging/mappings/LinearMappingsBuilder.scala [157:174]
private def getTopLevelJarPath(node: PackagedProjectNode): String = node.packagingOptions.packageMethod match {
case PackagingMethod.Skip() =>
throw new MappingBuildException(s"$node cannot be a top-level project")
case PackagingMethod.MergeIntoParent() =>
throw new MappingBuildException(s"$node cannot be a top-level project")
case PackagingMethod.MergeIntoOther(_) =>
throw new MappingBuildException(s"$node cannot be a top-level project")
case PackagingMethod.DepsOnly("") =>
mkProjectJarDefaultPath(node)
case PackagingMethod.DepsOnly(nonEmptyPath) =>
nonEmptyPath
case PackagingMethod.Standalone("", _) =>
mkProjectJarDefaultPath(node)
case PackagingMethod.Standalone(nonEmptyPath, _) =>
nonEmptyPath
case PackagingMethod.PluginModule(moduleName, _) =>
mkPluginModulePath(moduleName)
}