Add reflection hints for Kotlin reflection on functions

Kotlin reflection API invocation on a specific function
may require iterating on all Java methods to find the right
Kotlin function. As a consequence, this commit adds introspection
hints on the class declared methods for all Kotlin beans since
the impact on the footprint is low.

Closes gh-29663

spring-context/src/main/java/org/springframework/context/aot/KotlinReflectionBeanRegistrationAotProcessor.java

@@ -0,0 +1,72 @@
+/*
+ * 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.context.aot;
+
+import org.springframework.aot.generate.GenerationContext;
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.beans.factory.aot.BeanRegistrationAotContribution;
+import org.springframework.beans.factory.aot.BeanRegistrationAotProcessor;
+import org.springframework.beans.factory.aot.BeanRegistrationCode;
+import org.springframework.beans.factory.support.RegisteredBean;
+import org.springframework.core.KotlinDetector;
+import org.springframework.lang.Nullable;
+
+/**
+ * AOT {@code BeanRegistrationAotProcessor} that adds additional hints
+ * required by Kotlin reflection.
+ *
+ * @author Sebastien Deleuze
+ * @since 6.0.4
+ */
+class KotlinReflectionBeanRegistrationAotProcessor implements BeanRegistrationAotProcessor {
+
+	@Nullable
+	@Override
+	public BeanRegistrationAotContribution processAheadOfTime(RegisteredBean registeredBean) {
+		Class<?> beanClass = registeredBean.getBeanClass();
+		if (KotlinDetector.isKotlinType(beanClass)) {
+			return new KotlinReflectionBeanRegistrationAotContribution(beanClass);
+		}
+		return null;
+	}
+
+	private static class KotlinReflectionBeanRegistrationAotContribution implements BeanRegistrationAotContribution {
+
+		private final Class<?> beanClass;
+
+		public KotlinReflectionBeanRegistrationAotContribution(Class<?> beanClass) {
+			this.beanClass = beanClass;
+		}
+
+		@Override
+		public void applyTo(GenerationContext generationContext, BeanRegistrationCode beanRegistrationCode) {
+			registerHints(this.beanClass, generationContext.getRuntimeHints());
+		}
+
+		private void registerHints(Class<?> type, RuntimeHints runtimeHints) {
+			if (KotlinDetector.isKotlinType(type)) {
+				runtimeHints.reflection().registerType(type, MemberCategory.INTROSPECT_DECLARED_METHODS);
+			}
+			Class<?> superClass = type.getSuperclass();
+			if (superClass != null) {
+				registerHints(superClass, runtimeHints);
+			}
+		}
+	}
+
+}