Open router and bean Kotlin DSL to allow building custom ones

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

@@ -76,7 +76,7 @@ fun beans(init: BeanDefinitionDsl.() -> Unit): BeanDefinitionDsl {
  * @author Sebastien Deleuze
  * @since 5.0
  */
-class BeanDefinitionDsl(private val condition: (ConfigurableEnvironment) -> Boolean = { true }) : ApplicationContextInitializer<GenericApplicationContext> {
+open class BeanDefinitionDsl(private val condition: (ConfigurableEnvironment) -> Boolean = { true }) : ApplicationContextInitializer<GenericApplicationContext> {
 
 	@PublishedApi
 	internal val registrations = arrayListOf<(GenericApplicationContext) -> Unit>()

spring-webflux/src/main/kotlin/org/springframework/web/reactive/function/server/RouterFunctionDsl.kt

@@ -60,7 +60,7 @@ fun router(routes: RouterFunctionDsl.() -> Unit) = RouterFunctionDsl().apply(rou
  * @since 5.0
  * @see <a href="https://youtrack.jetbrains.com/issue/KT-15667">Kotlin issue about supporting ::foo for member functions</a>
  */
-class RouterFunctionDsl {
+open class RouterFunctionDsl {
 
 	private val routes = mutableListOf<RouterFunction<ServerResponse>>()