Add transformer app for function sample

function-samples/transform-user-clicks-per-region/src/main/java/org/springframework/cloud/dataflow/samples/transform/UserClicksPerRegionTransformer.java

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+/*
+ * Copyright 2015-2016 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.cloud.dataflow.samples.transform;
+
+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.support.MutableMessage;
+import org.springframework.messaging.Message;
+
+@SpringBootApplication
+public class UserClicksPerRegionTransformer {
+
+
+	@Bean
+	public Function<Message<?>, Message<UserClicksPerRegion>> transform() {
+		return message -> {
+			String regions = (String) message.getHeaders().get("kafka_receivedMessageKey");
+			Long clicks = (Long) message.getPayload();
+			return new MutableMessage<>(new UserClicksPerRegion(regions, clicks));
+		};
+	}
+
+	public class UserClicksPerRegion  {
+
+		private String regions;
+
+		public UserClicksPerRegion(String regions, Long clicks) {
+			this.regions = regions;
+			this.clicks = clicks;
+		}
+
+		private Long clicks;
+
+		public String getRegions() {
+			return regions;
+		}
+
+		public Long getClicks() {
+			return clicks;
+		}
+	}
+
+	public static void main(String[] args) {
+		SpringApplication.run(UserClicksPerRegionTransformer.class, args);
+	}
+}

function-samples/transform-user-clicks-per-region/src/main/resources/application.yml

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+spring.cloud.stream.bindings.input:
+  consumer:
+    useNativeEncoding: true
+spring.cloud.stream.kafka.binder.configuration.key:
+  deserializer: org.apache.kafka.common.serialization.StringDeserializer
+spring.cloud.stream.kafka.binder.configuration.value:
+  deserializer: org.apache.kafka.common.serialization.LongDeserializer
+
+spring.cloud.function.definition: transform
+spring.cloud.stream.function.bindings.transform-in-0: input
+spring.cloud.stream.function.bindings.transform-out-0: output