gradle：调用另一个项目下的坡度文件

梯度5.4.1

/project-foo/build.gradle


/project-bar/settings.gradle   
/project-bar/common-gradle/build-hello.gradle
/project-bar/common-gradle/build-world.gradle 

project bar/common gradle不是项目目录，但仅包含常用的gradle文件

project foo/build.gradle调用项目栏下的build-hello.gradle，如下所示：

task build_hello(type: GradleBuild) {
    dir = "${rootProject.buildDir}/build-hello"
    buildFile = file("/project-bar/common-gradle/build-hello.gradle")
    ...
}  

assemble.dependsOn build_hello

生成项目foo时，出现错误：

Build file '/project-bar/common-gradle/hello.gradle' is not 
part of the build defined by settings file
'/project-bar/settings.gradle'. If this is an unrelated build, 
it must have its own settings file.

如果删除/project bar/settings.gradle，则构建项目foo将正常工作。错误消息是什么意思

是否应在不是项目目录的公共gradle目录下创建settings.gradle？它的内容是什么