Gradle - configuration for sibling and interlinked projects - eclipse

Question

I'm try to configure sibling projects with several dependencies (I'm talking about project dependencies, not artifact dependencies)
So the structure is something like:
A (needs B)
B (needs C)
C
I need to set correctly these dependencies. In particular, I'm using the Eclipse integration, so the goal is to get Gradle -> Refresh all set the correct dependencies among the relative Eclipse projects (however, I believe this question is independent of Eclipse).
Notice that there is only a logical hierarchical layout, not physical (and it will stay that way).
I have read about the use of includeFlat, but probably I'm still missing something.
If we look only at B and C, then I can have them work correctly, by:
In B/settings.gradle : includeFlat 'C'
In B/build.gradle : compile project(':C')
This works fine for B.
Now, A needs B. So what I thought was: I just need to do the same thing between A and B:
In A/settings.gradle : includeFlat 'B'
In A/build.gradle : compile project(':B')
I did expect that when refreshing A, the transitive dependency A -> B -> C would work, but somewhere it breaks and I get:
Project with path ':C' could not be found in project ':B'
What I'm guessing is that B/settings.gradle is not being read. Why is that?
Could someone tell me what I am not understanding?

Answer 1

In a Gradle multi-project build, only one settings.gradle file can be used at a time. Since project B depends on C and project B is part of the multi-project build, you need to include project C in any settings.gradle file that uses project B (assuming you're using project dependencies instead of artifact dependencies).
Note that you can tell Gradle which settings.gradle file to use for each build with the -c command line option, but the build for A is never going to work unless B and all of its project dependencies are included.
Also note that multi-project builds always define a single "root" project, which is defined by where the settings.gradle file is. So if project A contains settings.gradle, it is the "root" project. However, in a flat layout, you can create a special directory named master to represent this and Gradle will automatically find your settings.gradle file there. Read about this here. Note that all of your build commands should typically be run from the "root" project, so if you use the Gradle wrapper, it should live there.
Assuming a flat layout, I would suggest this structure:
A/
build.gradle
src/
main/
java/
B/
build.gradle
src/
main/
java/
C/
build.gradle
src/
main/
java/
master/
build.gradle
gradle/
wrapper/
gradle-wrapper.jar
gradle-wrapper.properties
gradlew
gradlew.bat
settings.gradle
And the contents of settings.gradle would be something like:
["A", "B", "C"].each {
includeFlat it
}