From 30494c1c1a9dbf5129fef410001ad25325f08442 Mon Sep 17 00:00:00 2001
From: Yaacov Rydzinski <yaacovCR@gmail.com>
Date: Fri, 3 Sep 2021 02:28:59 +0300
Subject: [PATCH] workaround for v16

---
 packages/delegate/src/prepareGatewayDocument.ts | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/packages/delegate/src/prepareGatewayDocument.ts b/packages/delegate/src/prepareGatewayDocument.ts
index 3601e3d55e5..974c1f4b731 100644
--- a/packages/delegate/src/prepareGatewayDocument.ts
+++ b/packages/delegate/src/prepareGatewayDocument.ts
@@ -411,6 +411,22 @@ function wrapConcreteTypes(
         }
       },
       [Kind.FIELD]: (node: FieldNode) => {
+        // workaround for v16 lack of visitorKeys
+        //
+        // in v15, we never enter subfields because we don't visit any keys for nodes of kind `Kind.FIELD`
+        // which automatically means we only visit 'root fields', no matter how nested they are in fragment
+        // nodes.
+        //
+        // In v16, visitorKeys is gone, and we have to enter child fields and explicitly exit by returning
+        // 'false'.
+        const parentType = typeInfo.getParentType();
+        if (parentType == null) {
+          return false;
+        }
+        if (!rootTypeNames.has(parentType.name)) {
+          return false;
+        }
+        // end-workaround
         const type = typeInfo.getType();
         if (type != null && isAbstractType(getNamedType(type))) {
           return {