Support import of idomatic testcontainer declaration classes

Add an `@ImportTestcontainers` annotation which can be used to import
idomatic testcontainer declaration classes.

Closes gh-35245

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-session-redis/src/test/java/smoketest/session/redis/TestPropertiesImportSampleSessionRedisApplication.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2012-2023 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 smoketest.session.redis;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.testcontainers.context.ImportTestcontainers;
+import org.springframework.boot.testsupport.testcontainers.RedisContainer;
+import org.springframework.test.context.DynamicPropertyRegistry;
+import org.springframework.test.context.DynamicPropertySource;
+
+public class TestPropertiesImportSampleSessionRedisApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.from(SampleSessionRedisApplication::main).with(ContainerConfiguration.class).run(args);
+	}
+
+	@ImportTestcontainers
+	static class ContainerConfiguration {
+
+		static RedisContainer container = new RedisContainer();
+
+		@DynamicPropertySource
+		static void containerProperties(DynamicPropertyRegistry properties) {
+			properties.add("spring.data.redis.host", container::getHost);
+			properties.add("spring.data.redis.port", container::getFirstMappedPort);
+		}
+
+	}
+
+}

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-session-redis/src/test/java/smoketest/session/redis/TestServiceConnectionImportSampleSessionRedisApplication.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2012-2023 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 smoketest.session.redis;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.testcontainers.context.ImportTestcontainers;
+import org.springframework.boot.testcontainers.service.connection.ServiceConnection;
+import org.springframework.boot.testsupport.testcontainers.RedisContainer;
+
+public class TestServiceConnectionImportSampleSessionRedisApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.from(SampleSessionRedisApplication::main).with(ContainerConfiguration.class).run(args);
+	}
+
+	@ImportTestcontainers
+	static class ContainerConfiguration {
+
+		@ServiceConnection // We don't need a name here because we have the container
+		static RedisContainer redisContainer = new RedisContainer();
+
+	}
+
+}