GH-801 Add CloudEvent SDK sample

Resolves #801

spring-cloud-function-samples/function-sample-cloudevent-sdk/src/main/java/io/spring/cloudevent/DemoApplication.java

@@ -0,0 +1,39 @@
+package io.spring.cloudevent;
+
+import java.net.URI;
+import java.util.UUID;
+import java.util.function.Function;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.builder.CloudEventBuilder;
+import io.cloudevents.spring.messaging.CloudEventMessageConverter;
+
+@SpringBootApplication
+public class DemoApplication {
+
+	public static void main(String[] args) throws Exception {
+	    SpringApplication.run(DemoApplication.class, args);
+	}
+
+	@Bean
+	public Function<CloudEvent, CloudEvent> echo() {
+		return ce -> {
+			System.out.println("Received: " + ce);
+			return CloudEventBuilder.from(ce)
+					.withId(UUID.randomUUID().toString())
+					.withSource(URI.create("https://spring.io/foos"))
+					.withType("io.spring.event.Foo")
+					.withData(ce.getData().toBytes())
+					.build();
+		};
+	}
+	
+	@Bean
+	public CloudEventMessageConverter cloudEventMessageConverter() {
+		return new CloudEventMessageConverter();
+	}
+}