Modifying AppSyncLambdaAuthorizerEvent to incude requestHeaders

Author: Prashant Vissa

aws-lambda-java-events/src/main/java/com/amazonaws/services/lambda/runtime/events/AppSyncLambdaAuthorizerEvent.java

@@ -30,6 +30,7 @@ public class AppSyncLambdaAuthorizerEvent {
 
     private RequestContext requestContext;
     private String authorizationToken;
+    private MutableMap<CharSequence, Any> requestHeaders;
 
     @Data
     @Builder(setterPrefix = "with")