Use lazy API in test-suites

Author: sarahchen6

gradle/test-suites.gradle

@@ -57,8 +57,8 @@ ext.addTestSuiteExtendingForDir = { testSuiteName, parentSuiteName, dirName ->
   }
 
   tasks.register("${testSuiteName}Jar", Jar) {
-    dependsOn(tasks.named("${testSuiteName}Classes").get())
-    from(sourceSets.named(testSuiteName).get().output)
+    dependsOn(tasks.named("${testSuiteName}Classes"))
+    from(sourceSets.named(testSuiteName).map { it.output })
     archiveClassifier = testSuiteName
   }