Use BeanRegistrationAotProcessor to provide hints for auditing.

This avoids having to touch modules to add something like ImportRuntimeHints(AuditingHints.ReactiveAuditingRuntimeHints.class) to the enabled auditing annotations.

Original Pull Request: #2624

src/main/java/org/springframework/data/aot/AuditingBeanRegistrationAotProcessor.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2022 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.data.aot;
+
+import org.springframework.beans.factory.aot.BeanRegistrationAotContribution;
+import org.springframework.beans.factory.aot.BeanRegistrationAotProcessor;
+import org.springframework.beans.factory.support.RegisteredBean;
+import org.springframework.data.aot.hint.AuditingHints;
+import org.springframework.data.domain.AuditorAware;
+import org.springframework.data.domain.ReactiveAuditorAware;
+import org.springframework.data.repository.util.ReactiveWrappers;
+import org.springframework.data.repository.util.ReactiveWrappers.ReactiveLibrary;
+import org.springframework.lang.Nullable;
+import org.springframework.util.ClassUtils;
+
+/**
+ * @author Christoph Strobl
+ * @since 3.0
+ */
+public class AuditingBeanRegistrationAotProcessor implements BeanRegistrationAotProcessor {
+
+	@Nullable
+	@Override
+	public BeanRegistrationAotContribution processAheadOfTime(RegisteredBean registeredBean) {
+
+		if (isAuditingHandler(registeredBean)) {
+			return (generationContext, beanRegistrationCode) -> new AuditingHints.AuditingRuntimeHints()
+					.registerHints(generationContext.getRuntimeHints(), registeredBean.getBeanFactory().getBeanClassLoader());
+		}
+		if (ReactiveWrappers.isAvailable(ReactiveLibrary.PROJECT_REACTOR) && isReactiveAuditorAware(registeredBean)) {
+			return (generationContext, beanRegistrationCode) -> new AuditingHints.ReactiveAuditingRuntimeHints()
+					.registerHints(generationContext.getRuntimeHints(), registeredBean.getBeanFactory().getBeanClassLoader());
+		}
+		return null;
+	}
+
+	boolean isAuditingHandler(RegisteredBean bean) {
+		return ClassUtils.isAssignable(AuditorAware.class, bean.getBeanClass());
+	}
+
+	boolean isReactiveAuditorAware(RegisteredBean bean) {
+		return ClassUtils.isAssignable(ReactiveAuditorAware.class, bean.getBeanClass());
+	}
+}