Provide bean conditional registration capabilities in BeanRegistrarDsl

Closes gh-36601

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

@@ -18,8 +18,8 @@ package org.springframework.beans.factory
 
 import org.springframework.beans.factory.BeanRegistry.SupplierContext
 import org.springframework.core.ParameterizedTypeReference
-import org.springframework.core.ResolvableType
 import org.springframework.core.env.Environment
+import kotlin.reflect.KClass
 
 /**
  * Contract for registering programmatically beans.
@@ -364,6 +364,28 @@ open class BeanRegistrarDsl(private val init: BeanRegistrarDsl.() -> Unit): Bean
 		return registry.registerBean(object: ParameterizedTypeReference<T>() {}, customizer)
 	}
 
+	/**
+	 * Determine whether a bean of the given name is already registered.
+	 * @param name the name of the bean
+	 * @since 7.1
+	 */
+	fun containsBean(name: String): Boolean = registry.containsBean(name)
+
+	/**
+	 * Determine whether a bean of the given type is already registered.
+	 * @param beanType the type of the bean
+	 * @since 7.1
+	 */
+	fun containsBean(beanType: KClass<*>): Boolean = registry.containsBean(beanType.java)
+
+	/**
+	 * Determine whether a bean of the given type is already registered.
+	 * @param T the type of the bean
+	 * @since 7.1
+	 */
+	inline fun <reified T : Any> containsBean(): Boolean =
+		registry.containsBean(object: ParameterizedTypeReference<T>() {})
+
 
 	/**
 	 * Context available from the bean instance supplier designed to give access

spring-context/src/test/kotlin/org/springframework/context/annotation/BeanRegistrarDslConfigurationTests.kt

@@ -84,7 +84,13 @@ class BeanRegistrarDslConfigurationTests {
 		assertThat(context.getBeanProvider<Bar>().singleOrNull()).isNotNull
 	}
 
+	@Test
+	fun containsBean() {
+		AnnotationConfigApplicationContext(ContainsBeanRegistrarKotlinConfiguration::class.java)
+	}
+
 	class Foo
+
 	data class Bar(val foo: Foo)
 	data class Baz(val message: String = "")
 	class Init  : InitializingBean {
@@ -145,4 +151,18 @@ class BeanRegistrarDslConfigurationTests {
 	private class ChainedBeanRegistrar : BeanRegistrarDsl({
 		register(SampleBeanRegistrar())
 	})
+
+	@Configuration
+	@Import(ContainsBeanRegistrar::class)
+	internal class ContainsBeanRegistrarKotlinConfiguration
+
+	private class ContainsBeanRegistrar : BeanRegistrarDsl({
+		assertThat(containsBean("foo")).isFalse()
+		assertThat(containsBean(Foo::class)).isFalse()
+		assertThat(containsBean<Foo>()).isFalse()
+		registerBean<Foo>("foo")
+		assertThat(containsBean("foo")).isTrue()
+		assertThat(containsBean(Foo::class)).isTrue()
+		assertThat(containsBean<Foo>()).isTrue()
+	})
 }