Fix gradle integeration tests

Fix test failure on Windows, where backslash was not escaped
in a build file. Also, remove obsolete test for Gradle 4.2,
because 4.3 is the minimum supported version.

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

@@ -28,22 +28,6 @@ class BuildCacheIT : BaseGradleIT() {
         private val GRADLE_VERSION = GradleVersionRequired.AtLeast("4.3")
     }
 
-    @Test
-    fun testNoCacheWithGradlePre43() = with(Project("simpleProject", GradleVersionRequired.Exact("4.2"))) {
-        // Check that even with the build cache enabled, the Kotlin tasks are not cacheable with Gradle < 4.3:
-        val optionsWithCache = defaultBuildOptions().copy(withBuildCache = true)
-
-        build("assemble", options = optionsWithCache) {
-            assertSuccessful()
-            assertNotContains("Packing task ':compileKotlin'")
-        }
-        build("clean", "assemble", options = optionsWithCache) {
-            assertSuccessful()
-            assertNotContains(":compileKotlin FROM-CACHE")
-            assertContains(":compileJava FROM-CACHE")
-        }
-    }
-
     @Test
     fun testKotlinCachingEnabledFlag() = with(Project("simpleProject", GRADLE_VERSION)) {
         prepareLocalBuildCache()
@@ -70,6 +54,7 @@ class BuildCacheIT : BaseGradleIT() {
         build("clean", "assemble") {
             assertSuccessful()
             assertContains(":compileKotlin FROM-CACHE")
+            assertContains(":compileJava FROM-CACHE")
         }
     }
 

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

@@ -97,7 +97,7 @@ class KaptIncrementalWithIsolatingApt : KaptIncrementalIT() {
             
             tasks.whenTaskAdded {
                 if (it.name == "kaptKotlin") {
-                  it.getInputs().files("${additionalInputs.canonicalPath}")
+                  it.getInputs().files("${additionalInputs.invariantSeparatorsPath}")
                 }
             }
         """.trimIndent()