Kapt: Add tests for the command-line 'kapt' tool

plugins/kapt3/kapt3-cli/testData/integration/simple/ap/META-INF/services/javax.annotation.processing.Processor

@@ -0,0 +1 @@
+apt.SampleApt

plugins/kapt3/kapt3-cli/testData/integration/simple/ap/Processor.kt

@@ -0,0 +1,25 @@
+package apt
+
+import javax.annotation.processing.*
+import javax.lang.model.SourceVersion
+import javax.lang.model.element.TypeElement
+import javax.tools.Diagnostic.Kind.*
+
+annotation class Anno
+
+class SampleApt : AbstractProcessor() {
+    override fun process(annotations: Set<TypeElement>, roundEnv: RoundEnvironment): Boolean {
+        for (element in roundEnv.getElementsAnnotatedWith(Anno::class.java)) {
+            val generatedSimpleName = element.simpleName.toString().capitalize()
+            processingEnv.filer.createSourceFile("generated.$generatedSimpleName").openWriter().use {
+                it.write("package generated;\npublic class $generatedSimpleName {}")
+            }
+        }
+
+        return true
+    }
+
+    override fun getSupportedOptions() = emptySet<String>()
+    override fun getSupportedSourceVersion() = SourceVersion.RELEASE_8
+    override fun getSupportedAnnotationTypes() = setOf("apt.Anno")
+}