diff --git a/examples/fastify/.meshrc.yml b/examples/fastify/.meshrc.yml
index 4b528585e71c1..fd50928942fab 100644
--- a/examples/fastify/.meshrc.yml
+++ b/examples/fastify/.meshrc.yml
@@ -1,3 +1,4 @@
+merger: bare
 sources:
   - name: Swapi
     handler:
@@ -5,3 +6,14 @@ sources:
         source: ./swagger/pets.json
         endpoint: >-
           http://localhost:4001
+        selectQueryOrMutationField:
+          - fieldName: post_pet_by_petId
+            type: query
+    transforms:
+      - filterSchema:
+          mode: bare
+          filters:
+            - Mutation.!*
+      - extend:
+          typeDefs: ./src/extensions/typeDefs.graphql
+          resolvers: ./src/extensions/resolvers
diff --git a/examples/fastify/src/extensions/resolvers.ts b/examples/fastify/src/extensions/resolvers.ts
new file mode 100644
index 0000000000000..610bfd0145c0f
--- /dev/null
+++ b/examples/fastify/src/extensions/resolvers.ts
@@ -0,0 +1,7 @@
+const resolvers = {
+  Pet: {
+    fullName: () => "full name"
+  }
+}
+
+export default resolvers;
diff --git a/examples/fastify/src/extensions/typeDefs.graphql b/examples/fastify/src/extensions/typeDefs.graphql
new file mode 100644
index 0000000000000..d5530006e6e40
--- /dev/null
+++ b/examples/fastify/src/extensions/typeDefs.graphql
@@ -0,0 +1,3 @@
+extend type Pet {
+  fullName: String
+}
diff --git a/examples/fastify/swagger/pets.json b/examples/fastify/swagger/pets.json
index f07d6d5dbe758..7dbb8a75072f8 100644
--- a/examples/fastify/swagger/pets.json
+++ b/examples/fastify/swagger/pets.json
@@ -2,7 +2,34 @@
   "openapi": "3.0.3",
   "paths": {
     "/pet/{petId}": {
-      "get": {
+      "post": {
+        "parameters": [
+          {
+            "name": "petId",
+            "in": "path",
+            "description": "ID of pet to return",
+            "required": true,
+            "schema": {
+              "type": "string"
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "successful operation",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Pet"
+                }
+              }
+            }
+          }
+        }
+      }
+    },
+    "/pet2/{petId}": {
+      "post": {
         "parameters": [
           {
             "name": "petId",