Check Kotlin code using Detekt

Closes gh-45583

Author: wilkinsona

buildSrc/build.gradle

@@ -36,6 +36,7 @@ dependencies {
 	implementation("commons-codec:commons-codec:${commonsCodecVersion}")
 	implementation("de.undercouch.download:de.undercouch.download.gradle.plugin:5.5.0")
 	implementation("dev.adamko.dokkatoo:dokkatoo-plugin:2.3.1")
+	implementation("io.gitlab.arturbosch.detekt:detekt-gradle-plugin:1.23.8")
 	implementation("io.spring.gradle.antora:spring-antora-plugin:0.0.1")
 	implementation("io.spring.javaformat:spring-javaformat-gradle-plugin:${javaFormatVersion}")
 	implementation("io.spring.nohttp:nohttp-gradle:0.0.11")

buildSrc/src/main/java/org/springframework/boot/build/KotlinConventions.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,6 +22,9 @@
 
 import dev.adamko.dokkatoo.DokkatooExtension;
 import dev.adamko.dokkatoo.formats.DokkatooHtmlPlugin;
+import io.gitlab.arturbosch.detekt.Detekt;
+import io.gitlab.arturbosch.detekt.DetektPlugin;
+import io.gitlab.arturbosch.detekt.extensions.DetektExtension;
 import org.gradle.api.Project;
 import org.gradle.api.tasks.SourceSet;
 import org.gradle.api.tasks.SourceSetContainer;
@@ -40,6 +43,7 @@
  * <li>Treat all warnings as errors
  * <li>Suppress version warnings
  * </ul>
+ * <li>Detekt plugin is applied to perform static analysis of Kotlin code
  * </ul>
  *
  * <p/>
@@ -48,18 +52,23 @@
  */
 class KotlinConventions {
 
+	private static final String JVM_TARGET = "17";
+
+	private static final String KOTLIN_VERSION = "1.7";
+
 	void apply(Project project) {
 		project.getPlugins().withId("org.jetbrains.kotlin.jvm", (plugin) -> {
 			project.getTasks().withType(KotlinCompile.class, this::configure);
 			project.getPlugins().withType(DokkatooHtmlPlugin.class, (dokkatooPlugin) -> configureDokkatoo(project));
+			configureDetekt(project);
 		});
 	}
 
 	private void configure(KotlinCompile compile) {
 		KotlinJvmOptions kotlinOptions = compile.getKotlinOptions();
-		kotlinOptions.setApiVersion("1.7");
-		kotlinOptions.setLanguageVersion("1.7");
-		kotlinOptions.setJvmTarget("17");
+		kotlinOptions.setApiVersion(KOTLIN_VERSION);
+		kotlinOptions.setLanguageVersion(KOTLIN_VERSION);
+		kotlinOptions.setJvmTarget(JVM_TARGET);
 		kotlinOptions.setAllWarningsAsErrors(true);
 		List<String> freeCompilerArgs = new ArrayList<>(kotlinOptions.getFreeCompilerArgs());
 		freeCompilerArgs.add("-Xsuppress-version-warnings");
@@ -91,4 +100,11 @@ private void configureDokkatoo(Project project) {
 		});
 	}
 
+	private void configureDetekt(Project project) {
+		project.getPlugins().apply(DetektPlugin.class);
+		DetektExtension detekt = project.getExtensions().getByType(DetektExtension.class);
+		detekt.getConfig().setFrom(project.getRootProject().file("src/detekt/config.yml"));
+		project.getTasks().withType(Detekt.class).configureEach((task) -> task.setJvmTarget(JVM_TARGET));
+	}
+
 }

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/actuator/cloudfoundry/customcontextpath/MyCloudFoundryConfiguration.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -69,4 +69,5 @@ class MyCloudFoundryConfiguration {
 			context.addServlet("cloudfoundry", servlet).addMapping("/*")
 		}
 	}
-}
+}
+

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/actuator/cloudfoundry/customcontextpath/MyReactiveCloudFoundryConfiguration.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -51,3 +51,4 @@ class MyReactiveCloudFoundryConfiguration {
 		}
 	}
 }
+

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/actuator/endpoints/health/reactivehealthindicators/MyReactiveHealthIndicator.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,4 +37,5 @@ class MyReactiveHealthIndicator : ReactiveHealthIndicator {
 		return  /**/ null
 	}
 
-}
+}
+

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/actuator/endpoints/health/writingcustomhealthindicators/MyHealthIndicator.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,4 +36,5 @@ class MyHealthIndicator : HealthIndicator {
 		return  /**/ 0
 	}
 
-}
+}
+

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/actuator/endpoints/implementingcustom/CustomData.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,4 +16,5 @@
 
 package org.springframework.boot.docs.actuator.endpoints.implementingcustom
 
-class CustomData(val name: String, val counter: Int)
+class CustomData(val name: String, val counter: Int)
+

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/actuator/endpoints/implementingcustom/MyEndpoint.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,4 +37,5 @@ class MyEndpoint {
 		// injects "test" and 42
 	}
 	// end::write[]
-}
+}
+

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/actuator/endpoints/info/writingcustominfocontributors/MyInfoContributor.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,4 +28,5 @@ class MyInfoContributor : InfoContributor {
 		builder.withDetail("example", Collections.singletonMap("key", "value"))
 	}
 
-}
+}
+

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/actuator/endpoints/security/exposeall/MySecurityConfiguration.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,3 +34,4 @@ class MySecurityConfiguration {
 	}
 
 }
+