Cleanup kotlin sources

1. remove unused imports
2. remove redundant semicolon
3. remove empty class body
4. remove redundant 'constructor' keyword
5. remove redundant 'Unit' return type
6. use non-null type if possible

See gh-38708

spring-boot-project/spring-boot/src/main/kotlin/org/springframework/boot/SpringApplicationExtensions.kt

@@ -21,7 +21,6 @@ import org.springframework.util.Assert
 import org.springframework.util.ClassUtils
 import org.springframework.util.ReflectionUtils
 import kotlin.reflect.KClass
-import kotlin.reflect.KType
 
 /**
  * Top-level function acting as a Kotlin shortcut allowing to write

spring-boot-project/spring-boot/src/test/kotlin/org/springframework/boot/context/properties/KotlinConfigurationPropertiesTests.kt

@@ -38,7 +38,7 @@ class KotlinConfigurationPropertiesTests {
 
 	@AfterEach
 	fun cleanUp() {
-		this.context.close();
+		this.context.close()
 	}
 
 	@Test //gh-18652
@@ -48,22 +48,22 @@ class KotlinConfigurationPropertiesTests {
 				RootBeanDefinition(BingProperties::class.java))
 		beanFactory.registerSingleton("foo", BingProperties(""))
 		this.context.register(EnableConfigProperties::class.java)
-		this.context.refresh();
+		this.context.refresh()
 	}
 
 	@Test
 	fun `type with constructor bound lateinit property can be bound`() {
 		this.context.register(EnableLateInitProperties::class.java)
-		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.context, "lateinit.inner.value=alpha");
-		this.context.refresh();
+		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.context, "lateinit.inner.value=alpha")
+		this.context.refresh()
 		assertThat(this.context.getBean(LateInitProperties::class.java).inner.value).isEqualTo("alpha")
 	}
 
 	@Test
 	fun `type with constructor bound lateinit property with default can be bound`() {
 		this.context.register(EnableLateInitPropertiesWithDefault::class.java)
-		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.context, "lateinit-with-default.inner.bravo=two");
-		this.context.refresh();
+		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.context, "lateinit-with-default.inner.bravo=two")
+		this.context.refresh()
 		val properties = this.context.getBean(LateInitPropertiesWithDefault::class.java)
 		assertThat(properties.inner.alpha).isEqualTo("apple")
 		assertThat(properties.inner.bravo).isEqualTo("two")
@@ -72,20 +72,16 @@ class KotlinConfigurationPropertiesTests {
 	@Test
 	fun `mutable data class properties can be imported`() {
 		this.context.register(MutableDataClassPropertiesImporter::class.java)
-		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.context, "mutable.prop=alpha");
-		this.context.refresh();
+		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.context, "mutable.prop=alpha")
+		this.context.refresh()
 		assertThat(this.context.getBean(MutableDataClassProperties::class.java).prop).isEqualTo("alpha")
 	}
 
 	@ConfigurationProperties(prefix = "foo")
-	class BingProperties(@Suppress("UNUSED_PARAMETER") bar: String) {
-
-	}
+	class BingProperties(@Suppress("UNUSED_PARAMETER") bar: String)
 
 	@EnableConfigurationProperties
-	class EnableConfigProperties {
-
-	}
+	class EnableConfigProperties
 
 	@ConfigurationProperties("lateinit")
 	class LateInitProperties {
@@ -97,9 +93,7 @@ class KotlinConfigurationPropertiesTests {
 	data class Inner(val value: String)
 
 	@EnableConfigurationProperties(LateInitPropertiesWithDefault::class)
-	class EnableLateInitPropertiesWithDefault {
-
-	}
+	class EnableLateInitPropertiesWithDefault
 
 	@ConfigurationProperties("lateinit-with-default")
 	class LateInitPropertiesWithDefault {
@@ -111,15 +105,12 @@ class KotlinConfigurationPropertiesTests {
 	data class InnerWithDefault(val alpha: String = "apple", val bravo: String = "banana")
 
 	@EnableConfigurationProperties(LateInitProperties::class)
-	class EnableLateInitProperties {
-
-	}
+	class EnableLateInitProperties
 
 	@EnableConfigurationProperties
 	@Configuration(proxyBeanMethods = false)
 	@Import(MutableDataClassProperties::class)
-	class MutableDataClassPropertiesImporter {
-	}
+	class MutableDataClassPropertiesImporter
 
 	@ConfigurationProperties(prefix = "mutable")
 	data class MutableDataClassProperties(

spring-boot-project/spring-boot/src/test/kotlin/org/springframework/boot/context/properties/bind/KotlinBindableRuntimeHintsRegistrarTests.kt

@@ -20,7 +20,6 @@ import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.springframework.aot.hint.MemberCategory
 import org.springframework.aot.hint.RuntimeHints
-import org.springframework.aot.hint.predicate.RuntimeHintsPredicates
 
 
 /**

spring-boot-project/spring-boot/src/test/kotlin/org/springframework/boot/context/properties/bind/KotlinDefaultBindConstructorProviderTests.kt

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package org.springframework.boot.context.properties.bind;
+package org.springframework.boot.context.properties.bind
 
 import org.assertj.core.api.Assertions.assertThat
 import org.assertj.core.api.Assertions.assertThatIllegalStateException
@@ -46,7 +46,7 @@ class KotlinDefaultBindConstructorProviderTests {
 	@Test
 	fun `type with primary and secondary annotated constructor should use secondary constructor for binding`() {
 		val bindConstructor = this.constructorProvider.getBindConstructor(ConstructorBindingOnSecondaryWithPrimaryConstructor::class.java, false)
-		assertThat(bindConstructor).isNotNull();
+		assertThat(bindConstructor).isNotNull()
 	}
 
 	@Test
@@ -116,12 +116,12 @@ class KotlinDefaultBindConstructorProviderTests {
 	@Test
 	fun `data class with default values should use constructor binding`() {
 		val bindConstructor = this.constructorProvider.getBindConstructor(ConstructorBindingDataClassWithDefaultValues::class.java, false)
-		assertThat(bindConstructor).isNotNull();
+		assertThat(bindConstructor).isNotNull()
 	}
 
 	class FooProperties
 
-	class PrimaryWithAutowiredSecondaryProperties constructor(val name: String?, val counter: Int = 42) {
+	class PrimaryWithAutowiredSecondaryProperties(val name: String?, val counter: Int = 42) {
 
 		@Autowired
 		constructor(@Suppress("UNUSED_PARAMETER") foo: String) : this(foo, 21)
@@ -133,9 +133,7 @@ class KotlinDefaultBindConstructorProviderTests {
 		constructor(@Suppress("UNUSED_PARAMETER") foo: String)
 	}
 
-	class AutowiredPrimaryProperties @Autowired constructor(val name: String?, val counter: Int = 42) {
-
-	}
+	class AutowiredPrimaryProperties @Autowired constructor(val name: String?, val counter: Int = 42)
 
 	class ConstructorBindingOnSecondaryAndAutowiredPrimaryProperties @Autowired constructor(val name: String?, val counter: Int = 42) {
 
@@ -149,7 +147,7 @@ class KotlinDefaultBindConstructorProviderTests {
 		constructor(@Suppress("UNUSED_PARAMETER") foo: String) : this(foo, 21)
 	}
 
-	class ConstructorBindingOnSecondaryWithPrimaryConstructor constructor(val name: String?, val counter: Int = 42) {
+	class ConstructorBindingOnSecondaryWithPrimaryConstructor(val name: String?, val counter: Int = 42) {
 
 		@ConstructorBinding
 		constructor(@Suppress("UNUSED_PARAMETER") foo: String) : this(foo, 21)