Fix SkipValidSpec (#2583)

For #2319

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

@@ -525,7 +525,7 @@ open class GenerateTask : DefaultTask() {
             }
 
             skipValidateSpec.ifNotEmpty { value ->
-                configurator.setValidateSpec(value)
+                configurator.setValidateSpec(!value)
             }
 
             generateAliasAsModel.ifNotEmpty { value ->

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

@@ -66,4 +66,64 @@ class GenerateTaskDslTest : TestBase()  {
         assertEquals(TaskOutcome.SUCCESS, result.task(":openApiGenerate")?.outcome,
                 "Expected a successful run, but found ${result.task(":openApiGenerate")?.outcome}")
     }
+
+    @Test
+    fun `openApiValidate should fail on invalid spec`() {
+        // Arrange
+        val projectFiles = mapOf(
+                "spec.yaml" to javaClass.classLoader.getResourceAsStream("specs/petstore-v3.0-invalid.yaml")
+        )
+
+        withProject(defaultBuildGradle, projectFiles)
+
+        // Act
+        val result = GradleRunner.create()
+                .withProjectDir(temp)
+                .withArguments("openApiGenerate")
+                .withPluginClasspath()
+                .buildAndFail()
+
+        // Assert
+        assertTrue(result.output.contains("issues with the specification"), "Unexpected/no message presented to the user for an invalid spec.")
+        assertEquals(TaskOutcome.FAILED, result.task(":openApiGenerate")?.outcome,
+                "Expected a failed run, but found ${result.task(":openApiValidate")?.outcome}")
+    }
+
+    @Test
+    fun `openApiValidate should ok skip spec validation`() {
+        // Arrange
+        val projectFiles = mapOf(
+                "spec.yaml" to javaClass.classLoader.getResourceAsStream("specs/petstore-v3.0-invalid.yaml")
+        )
+
+        withProject("""
+        plugins {
+          id 'org.openapi.generator'
+        }
+        openApiGenerate {
+            generatorName = "kotlin"
+            inputSpec = file("spec.yaml").absolutePath
+            outputDir = file("build/kotlin").absolutePath
+            apiPackage = "org.openapitools.example.api"
+            invokerPackage = "org.openapitools.example.invoker"
+            modelPackage = "org.openapitools.example.model"
+            skipValidateSpec = true
+            configOptions = [
+                    dateLibrary: "java8"
+            ]
+        }
+    """.trimIndent(), projectFiles)
+
+        // Act
+        val result = GradleRunner.create()
+                .withProjectDir(temp)
+                .withArguments("openApiGenerate")
+                .withPluginClasspath()
+                .build()
+
+        // Assert
+        assertTrue(result.output.contains("validation has been explicitly disabled"), "Unexpected/no message presented to the user for an invalid spec.")
+        assertEquals(TaskOutcome.SUCCESS, result.task(":openApiGenerate")?.outcome,
+                "Expected a successful run, but found ${result.task(":openApiGenerate")?.outcome}")
+    }
 }

modules/openapi-generator-maven-plugin/src/main/java/org/openapitools/codegen/plugin/CodeGenMojo.java

@@ -464,7 +464,7 @@ public class CodeGenMojo extends AbstractMojo {
             }
 
             if (skipValidateSpec != null) {
-                configurator.setSkipOverwrite(skipValidateSpec);
+                configurator.setValidateSpec(!skipValidateSpec);
             }
 
             if (logToStderr != null) {