我有一个多模块SBT项目，它在第一个模块期间将源写入unmanagedSourceDirectories，然后在以后的模块中使用这些内容（此过程重复）。项目结构如下所示：
root
+ gen - writes content to useA/target/generated-sources
+ useA - writes content to useB/target/generated-sources
+ useB - writes content to useC/target/generated-sources
+ etc....
unmanagedSourceDirectories定义如下
root
+ gen
+ useA - unmanagedSourceDirectories=useA/target/generated-sources
+ useB - unmanagedSourceDirectories=useB/target/generated-sources
+ etc...
有没有办法实现我想要的目标？