Working with multi-project builds

Let's start with a simple multi-project structure. We have a root project called garden with two other projects, tree and flower. The project structure is as follows:

garden/
    tree/
    flower/

We will add a new task printInfo to each of these projects. The task will print out the name of the project to System.out. We must add a file build.gradle to each project, with the following contents:

task printInfo << {
    println "This is ${project.name}"
}

To execute the task for each project, we must first enter the correct directory and then invoke the task with Gradle. Or, we run build.gradle for a specific project with the -b argument of Gradle. We get the following output, if we run the task for each project:

garden $ gradle -q printInfo
This is garden
garden $ cd tree
tree $ gradle -q printInfo
This is tree
tree $ cd ..
garden $ gradle -b flower/build.gradle printInfo
This is flower

We have multiple projects, but we haven't used Gradle's support for...