Another commit for #71. Looks like the awaitInitialization method needs to be called after the resources are defined

Author: sapessi

README.md

@@ -93,6 +93,9 @@ public class LambdaHandler implements RequestHandler<AwsProxyRequest, AwsProxyRe
     public AwsProxyResponse handleRequest(AwsProxyRequest awsProxyRequest, Context context) {
         if (!initialized) {
             defineRoutes();
+            // it's important to call the awaitInitialization method not to run into race 
+            // conditions as routes are loaded asynchronously
+            Spark.awaitInitialization();
             initialized = true;
         }
         return handler.proxy(awsProxyRequest, context);

samples/spark/pet-store/src/main/java/com/amazonaws/serverless/sample/spark/LambdaHandler.java

@@ -24,6 +24,7 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import spark.Spark;
 
 import javax.ws.rs.core.Response;
 import java.util.UUID;
@@ -45,6 +46,7 @@ public AwsProxyResponse handleRequest(AwsProxyRequest awsProxyRequest, Context c
             try {
                 handler = SparkLambdaContainerHandler.getAwsProxyHandler();
                 defineResources();
+                Spark.awaitInitialization();
             } catch (ContainerInitializationException e) {
                 log.error("Cannot initialize Spark application", e);
                 return null;