allow to provide no header (but still \n) for msearch

src/main/java/org/elasticsearch/action/search/MultiSearchRequest.java

@@ -77,6 +77,7 @@ public class MultiSearchRequest implements ActionRequest {
             }
 
             // now parse the action
+            if (nextMarker - from > 0) {
                 XContentParser parser = xContent.createParser(data, from, nextMarker - from);
                 try {
                     // Move to START_OBJECT, if token is null, its an empty data
@@ -107,6 +108,7 @@ public class MultiSearchRequest implements ActionRequest {
                 } finally {
                     parser.close();
                 }
+            }
 
             // move pointers
             from = nextMarker + 1;