== Step 1. Understanding the Version Catalog
A version catalog is used to declare all direct dependencies of a project in a central location.

It is created in by Gradle init in `gradle/libs.versions.toml` and referenced in subproject build files.

.libs.versions.toml
[source,text]
----
[versions]
guava = "32.1.2-jre"
junit-jupiter = "5.10.0"

[libraries]
guava = { module = "com.google.guava:guava", version.ref = "guava" }

[.multi-language-sample]
=====
[source,kotlin]
----
.
├── a-subproject
│   └── build.gradle.kts
├── settings.gradle.kts
├── gradle
│   └── wrapper
│       ├── gradle-wrapper.jar
│       └── gradle-wrapper.properties
├── gradlew
└── gradlew.bat
----
=====
[.multi-language-sample]
=====
[source,groovy]
----
.
├── a-subproject
│   └── build.gradle
├── settings.gradle
├── gradle

 * This project provides the "platform" for the Gradle distribution.
 * We want the versions that are packaged in the distribution to be used everywhere (e.g. in all test scenarios)
 * Hence, we lock the versions down here for all other subprojects.
 *
 * Note:
 * We use strictly here because we do not have any better means to do this at the moment.
 * Ideally we wound be able to say "lock down all the versions of the dependencies resolved for the distribution"
 */

    // Because this is done directly by the plugin application logic, we can't use a ComponentMetadataRule to exclude it.
    // See: https://github.com/gradle/guides/blob/ba018cec535d90f75876bfcca29381d213a956cc/subprojects/gradle-guides-plugin/src/main/java/org/gradle/docs/samples/internal/SamplesDocumentationPlugin.java#L335
    exclude([group: "org.slf4j", module: "slf4j-simple"])
}

dependencies {

```java
/**
 * <pre><code class="language-kotlin">
 * project.ext.prop1 = "foo"
 * task doStuff {
 *     ext.prop2 = "bar"
 * }
 * subprojects { ext.${prop3} = false }
 * </code></pre>
 */
```

        given:
        mavenRepo.module("org.gradle", "dep", "1.1").publish()

        and:
        settingsFile << "include ':main', ':util'"

        buildFile << """
subprojects {
    apply plugin: 'java-library'
    apply plugin: 'maven-publish'
    group = 'my.org'
    version = '1.0'
    repositories {
        maven { url "${mavenRepo.uri}" }
    }
    publishing {

    def "can have cycle in project dependencies"() {
        given:
        createDirs("a", "b", "c")
        file('settings.gradle') << "include 'a', 'b', 'c'"

        and:
        buildFile << """

subprojects {
    apply plugin: 'base'
    configurations {
        first
        other
        'default' {
            extendsFrom first
        }
    }
    task jar(type: Jar)
    artifacts {

            projectConfigured(":buildSrc")
            modelsCreated(":")
            problem("Build file 'build.gradle': line 3: Project ':' cannot access 'Project.plugins' functionality on subprojects via 'allprojects'", 2)
        }

        when:
        executer.withArguments(ENABLE_CLI, WARN_PROBLEMS_CLI_OPT)
        def model2 = fetchModel()

        then:

            def buildFile = new File(invocation.projectDir, "build.gradle")
            buildFile << """
                def finalizerTask = tasks.register("testFinalizer")
                subprojects {
                    tasks.withType(com.android.build.gradle.tasks.factory.AndroidUnitTest) { testTask ->
                        testTask.finalizedBy(finalizerTask)
                        finalizerTask.configure {

     *   include 'baz'
     *   project(':baz').projectDir = file('foo/baz')
     *
     *   // include many projects whose project dirs do not match the logical project paths
     *   file('subprojects').eachDir { dir ->
     *     include dir.name
     *     project(":${dir.name}").projectDir = dir
     *   }
     * </pre>
     *
     * @param projectPaths the projects to add.
     */