Fix resolution of Java Usage artifacts for configurations with no usage

When Gradle resolves a dependency on a publication with no metadata
(or with metadata disabled), it represents it as two variants, one with
Usage `java-api`, the other with `java-runtime`. It turns out that the
`java-api` one does not contain transitive dependencies with Maven scope
`runtime`.

This commit makes the Kotlin Gradle plugin disambiguation rules behave
the same way as those defined in the JavaBasePlugin: when no Usage is
requested, prefer the runtime usages as they are more complete.

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/VariantAwareDependenciesIT.kt

@@ -224,6 +224,23 @@ class VariantAwareDependenciesIT : BaseGradleIT() {
         testResolveAllConfigurations("sample-lib")
     }
 
+    @Test
+    fun testConfigurationsWithNoExplicitUsageResolveRuntime() =
+    // Starting with Gradle 5.0, plain Maven dependencies are represented as two variants, and resolving them to the API one leads
+    // to transitive dependencies left out of the resolution results. We need to ensure that our attributes schema does not lead to the API
+    // variants chosen over the runtime ones when resolving a configuration with no required Usage:
+        with(Project("simpleProject", GradleVersionRequired.AtLeast("5.0-milestone-1"))) {
+            setupWorkingDir()
+            gradleBuildScript().appendText("\ndependencies { compile 'org.jetbrains.kotlin:kotlin-compiler-embeddable' }")
+
+            testResolveAllConfigurations {
+                assertContains(">> :compile --> kotlin-compiler-embeddable-${defaultBuildOptions().kotlinVersion}.jar")
+
+                // Check that the transitive dependencies with 'runtime' scope are also available:
+                assertContains(">> :compile --> kotlin-script-runtime-${defaultBuildOptions().kotlinVersion}.jar")
+            }
+        }
+
     private fun Project.embedProject(other: Project) {
         setupWorkingDir()
         other.setupWorkingDir()

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/KotlinUsages.kt

@@ -71,10 +71,10 @@ object KotlinUsages {
                 details.closestMatch(candidateValues.single { it?.name == KOTLIN_RUNTIME }!!)
             }
             if (JAVA_API in candidateNames && JAVA_RUNTIME_JARS in candidateNames && values.none { it in candidateNames }) {
-                details.closestMatch(candidateValues.single { it?.name == JAVA_API }!!)
+                details.closestMatch(candidateValues.single { it?.name == JAVA_RUNTIME_JARS }!!)
             }
             if (JAVA_API in candidateNames && JAVA_RUNTIME in candidateNames && values.none { it in candidateNames }) {
-                details.closestMatch(candidateValues.single { it?.name == JAVA_API }!!)
+                details.closestMatch(candidateValues.single { it?.name == JAVA_RUNTIME }!!)
             }
             if (JAVA_RUNTIME_CLASSES in candidateNames && JAVA_RUNTIME_RESOURCES in candidateNames && KOTLIN_RUNTIME in candidateNames) {
                 closestMatch(candidateValues.single { it?.name == KOTLIN_RUNTIME }!!)