Add Spring Integration Sample

Demonstrates how `IntegrationFlow` can be exposed as a `Function`

* Upgrade to the latest dependencies

* Polishing
Resolves #214

spring-cloud-function-samples/function-sample-spring-integration/src/main/java/example/FunctionSampleSpringIntegrationApplication.java

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+/*
+ * Copyright 2019 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
+ *
+ *      http://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 example;
+
+import java.util.function.Function;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+import org.springframework.integration.dsl.IntegrationFlow;
+import org.springframework.integration.dsl.IntegrationFlows;
+import org.springframework.integration.handler.LoggingHandler;
+import org.springframework.messaging.Message;
+
+@SpringBootApplication
+public class FunctionSampleSpringIntegrationApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(FunctionSampleSpringIntegrationApplication.class, args);
+	}
+
+	@Bean
+	public IntegrationFlow uppercaseFlow() {
+		return IntegrationFlows.from(MessageFunction.class, "uppercase")
+				.<String, String>transform(String::toUpperCase)
+				.logAndReply(LoggingHandler.Level.WARN);
+	}
+
+	public interface MessageFunction extends Function<Message<String>, Message<String>> {
+
+	}
+
+}

spring-cloud-function-samples/function-sample-spring-integration/src/main/resources/application.properties

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+

spring-cloud-function-samples/function-sample-spring-integration/src/test/java/example/FunctionSampleSpringIntegrationApplicationTests.java

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+/*
+ * Copyright 2019 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
+ *
+ *      http://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 example;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.MediaType;
+import org.springframework.test.context.junit4.SpringRunner;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+public class FunctionSampleSpringIntegrationApplicationTests {
+
+	@Autowired
+	private TestRestTemplate restTemplate;
+
+	@Test
+	public void upperCase() {
+		HttpHeaders httpHeaders = new HttpHeaders();
+		httpHeaders.setContentType(MediaType.APPLICATION_JSON);
+		HttpEntity<String> requestEntity = new HttpEntity<>("[\"foo\", \"bar\"]", httpHeaders);
+		HttpEntity<String> result = this.restTemplate.postForEntity("/uppercase", requestEntity, String.class);
+		assertEquals("[\"FOO\",\"BAR\"]", result.getBody());
+	}
+
+}