Refine BeanFactory extensions to avoid type erasure when possible

Closes gh-31439

spring-beans/src/main/kotlin/org/springframework/beans/factory/BeanFactoryExtensions.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -21,14 +21,17 @@ import org.springframework.core.ResolvableType
 
 /**
  * Extension for [BeanFactory.getBean] providing a `getBean<Foo>()` variant.
+ * This extension is not subject to type erasure and retains actual generic type arguments.
  *
  * @author Sebastien Deleuze
  * @since 5.0
  */
-inline fun <reified T : Any> BeanFactory.getBean(): T = getBean(T::class.java)
+inline fun <reified T : Any> BeanFactory.getBean(): T =
+		getBeanProvider<T>().getObject()
 
 /**
  * Extension for [BeanFactory.getBean] providing a `getBean<Foo>("foo")` variant.
+ * Like the original Java method, this extension is subject to type erasure.
  *
  * @see BeanFactory.getBean(String, Class<T>)
  * @author Sebastien Deleuze
@@ -40,13 +43,14 @@ inline fun <reified T : Any> BeanFactory.getBean(name: String): T =
 
 /**
  * Extension for [BeanFactory.getBean] providing a `getBean<Foo>(arg1, arg2)` variant.
+ * This extension is not subject to type erasure and retains actual generic type arguments.
  *
  * @see BeanFactory.getBean(Class<T>, Object...)
  * @author Sebastien Deleuze
  * @since 5.0
  */
 inline fun <reified T : Any> BeanFactory.getBean(vararg args:Any): T =
-		getBean(T::class.java, *args)
+		getBeanProvider<T>().getObject(*args)
 
 /**
  * Extension for [BeanFactory.getBeanProvider] providing a `getBeanProvider<Foo>()` variant.

spring-beans/src/test/kotlin/org/springframework/beans/factory/BeanFactoryExtensionsTests.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -16,10 +16,12 @@
 
 package org.springframework.beans.factory
 
+import io.mockk.every
 import io.mockk.mockk
 import io.mockk.verify
 import org.junit.jupiter.api.Test
 import org.springframework.core.ResolvableType
+import kotlin.reflect.full.createInstance
 
 /**
  * Mock object based tests for BeanFactory Kotlin extensions.
@@ -32,8 +34,10 @@ class BeanFactoryExtensionsTests {
 
 	@Test
 	fun `getBean with reified type parameters`() {
+		val foo = Foo()
+		every { bf.getBeanProvider<Foo>(ofType<ResolvableType>()).getObject() } returns foo
 		bf.getBean<Foo>()
-		verify { bf.getBean(Foo::class.java) }
+		verify { bf.getBeanProvider<ObjectProvider<Foo>>(ofType<ResolvableType>()).getObject() }
 	}
 
 	@Test
@@ -47,8 +51,10 @@ class BeanFactoryExtensionsTests {
 	fun `getBean with reified type parameters and varargs`() {
 		val arg1 = "arg1"
 		val arg2 = "arg2"
-		bf.getBean<Foo>(arg1, arg2)
-		verify { bf.getBean(Foo::class.java, arg1, arg2) }
+		val bar = Bar(arg1, arg2)
+		every { bf.getBeanProvider<Bar>(ofType<ResolvableType>()).getObject(arg1, arg2) } returns bar
+		bf.getBean<Bar>(arg1, arg2)
+		verify { bf.getBeanProvider<Bar>(ofType<ResolvableType>()).getObject(arg1, arg2) }
 	}
 
 	@Test
@@ -58,4 +64,7 @@ class BeanFactoryExtensionsTests {
 	}
 
 	class Foo
+
+	@Suppress("UNUSED_PARAMETER")
+	class Bar(arg1: String, arg2: String)
 }