Add Kotlin extensions for bean registration and retrieval

Issue: SPR-15048

spring-context/src/main/kotlin/org/springframework/context/support/GenericApplicationContextExtension.kt

@@ -0,0 +1,47 @@
+package org.springframework.context.support
+
+import org.springframework.beans.factory.config.BeanDefinitionCustomizer
+import java.util.function.Supplier
+import kotlin.reflect.KClass
+
+/**
+ * Extension for [GenericApplicationContext] providing [KClass] based API and
+ * avoiding specifying a class parameter for the [Supplier] based variant thanks to
+ * Kotlin reified type parameters.
+ *
+ * @since 5.0
+ */
+object GenericApplicationContextExtension {
+
+	/**
+	 * @see GenericApplicationContext.registerBean(Class<T>, BeanDefinitionCustomizer...)
+	 */
+	fun <T : Any> GenericApplicationContext.registerBean(beanClass: KClass<T>,
+			vararg customizers: BeanDefinitionCustomizer) {
+					registerBean(beanClass.java, *customizers)
+	}
+
+	/**
+	 * @see GenericApplicationContext.registerBean(String, Class<T>, BeanDefinitionCustomizer...)
+	 */
+	fun <T : Any> GenericApplicationContext.registerBean(beanName: String, beanClass: KClass<T>,
+			vararg customizers: BeanDefinitionCustomizer) {
+					registerBean(beanName, beanClass.java, *customizers)
+	}
+
+	/**
+	 * @see GenericApplicationContext.registerBean(Class<T>, Supplier<T>, BeanDefinitionCustomizer...)
+	 */
+	inline fun <reified T : Any> GenericApplicationContext.registerBean(supplier: Supplier<T>,
+			vararg customizers: BeanDefinitionCustomizer) {
+					registerBean(T::class.java, supplier, *customizers)
+	}
+
+	/**
+	 * @see GenericApplicationContext.registerBean(String, Class<T>, Supplier<T>, BeanDefinitionCustomizer...)
+	 */
+	inline fun <reified T : Any> GenericApplicationContext.registerBean(name: String,
+			supplier: Supplier<T>, vararg customizers: BeanDefinitionCustomizer) {
+					registerBean(name, T::class.java, supplier, *customizers)
+	}
+}

spring-context/src/test/kotlin/org/springframework/context/support/GenericApplicationContextExtensionTests.kt

@@ -0,0 +1,45 @@
+package org.springframework.context.support
+
+import org.junit.Assert.assertNotNull
+import org.junit.Test
+import org.springframework.context.support.GenericApplicationContextExtension.registerBean
+import org.springframework.beans.factory.BeanFactoryExtension.getBean
+import java.util.function.Supplier
+
+class GenericApplicationContextExtensionTests {
+
+	@Test
+	fun registerBeanWithClass() {
+		val context = GenericApplicationContext()
+		context.registerBean(BeanA::class)
+		context.refresh()
+		assertNotNull(context.getBean(BeanA::class))
+	}
+
+	@Test
+	fun registerBeanWithNameAndClass() {
+		val context = GenericApplicationContext()
+		context.registerBean("a", BeanA::class)
+		context.refresh()
+		assertNotNull(context.getBean("a"))
+	}
+
+	@Test
+	fun registerBeanWithSupplier() {
+		val context = GenericApplicationContext()
+		context.registerBean(Supplier { BeanA() })
+		context.refresh()
+		assertNotNull(context.getBean(BeanA::class))
+	}
+
+	@Test
+	fun registerBeanWithNameAndSupplier() {
+		val context = GenericApplicationContext()
+		context.registerBean("a",  Supplier { BeanA() })
+		context.refresh()
+		assertNotNull(context.getBean("a"))
+	}
+
+	internal class BeanA
+
+}