GH-437 Pass ExecutionContext via MessageHeader

Caching it as part of ApplicationContext was not the right idea so this changes it

spring-cloud-function-samples/function-sample-azure/src/main/java/example/Config.java

@@ -16,14 +16,14 @@
 
 package example;
 
-import java.io.IOException;
 import java.util.Map;
 import java.util.function.Function;
 
-import com.fasterxml.jackson.databind.ObjectMapper;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.cloud.function.json.JsonMapper;
 import org.springframework.context.annotation.Bean;
+import org.springframework.messaging.Message;
 
 import com.microsoft.azure.functions.ExecutionContext;
 
@@ -35,12 +35,12 @@ public class Config {
 	}
 
 	@Bean
-	public Function<String, String> uppercase(ExecutionContext context) {
-		return value -> {
-			ObjectMapper mapper = new ObjectMapper();
-
+	public Function<Message<String>, String> uppercase(JsonMapper mapper) {
+		return message -> {
+			String value = message.getPayload();
+			ExecutionContext context = (ExecutionContext) message.getHeaders().get("executionContext");
 			try {
-				Map<String, String> map = mapper.readValue(value, Map.class);
+				Map<String, String> map = mapper.fromJson(value, Map.class);
 
 				if(map != null)
 					map.forEach((k, v) -> map.put(k, v != null ? v.toUpperCase() : null));
@@ -48,8 +48,9 @@ public class Config {
 				if(context != null)
 					context.getLogger().info(new StringBuilder().append("Function: ").append(context.getFunctionName()).append(" is uppercasing ").append(value.toString()).toString());
 
-				return mapper.writeValueAsString(map);
-			} catch (IOException e) {
+				return mapper.toString(map);
+			} catch (Exception e) {
+				e.printStackTrace();
 				if(context != null)
 					context.getLogger().severe("Function could not parse incoming request");