Minor improvements to Gradle plugin (#14097)

* minor improvements to gradle plugin, test

* update gradle plugin doc

* fix out

Author: wing328

modules/openapi-generator-gradle-plugin/README.adoc

@@ -378,6 +378,11 @@ apply plugin: 'org.openapi.generator'
 |String
 |mustache
 |Templating engine: "mustache" (default) or "handlebars" (beta)
+
+|cleanupOutput
+|Boolean
+|false
+|Defines whether the output directory should be cleaned up before generating the output.
 |===
 
 [NOTE]

modules/openapi-generator-gradle-plugin/src/main/kotlin/org/openapitools/generator/gradle/plugin/tasks/GenerateTask.kt

@@ -523,6 +523,9 @@ open class GenerateTask : DefaultTask() {
         cleanupOutput.ifNotEmpty { cleanup ->
             if (cleanup) {
                 project.delete(outputDir)
+                val out = services.get(StyledTextOutputFactory::class.java).create("openapi")
+                out.withStyle(StyledTextOutput.Style.Success)
+                out.println("Cleaned up output directory ${outputDir.get()} before code generation (cleanupOutput set to true).")
             }
         }
 

modules/openapi-generator-gradle-plugin/src/test/kotlin/GenerateTaskDslTest.kt

@@ -136,7 +136,7 @@ class GenerateTaskDslTest : TestBase() {
         )
         withProject(defaultBuildGradle, projectFiles)
 
-        val oldFile = File(temp, "build/kotlin/should-be-removed")
+        val oldFile = File(temp, "build/kotlin/should-not-be-removed")
         oldFile.mkdirs()
         oldFile.createNewFile()
 
@@ -153,7 +153,7 @@ class GenerateTaskDslTest : TestBase() {
             "User friendly generate notice is missing."
         )
 
-        assertTrue(oldFile.exists(), "Old files should have been removed")
+        assertTrue(oldFile.exists(), "Old files should NOT have been removed")
 
         assertEquals(
             TaskOutcome.SUCCESS, result.task(":openApiGenerate")?.outcome,