Bug: Cache writes of incremental responses uses incorrect parent key (custom cache keys)

[calvincestari]

When using custom cache keys the cache records written as a result of an incremental response do not use the correct parent entity cache key and instead default to the behaviour as if no custom cache key was provided.

Here is incremental cache data when not using a custom cache key

"_id"	"key"	"record"
4	"QUERY_ROOT"	"{""allProducts"":[{""$reference"":""QUERY_ROOT.allProducts.0""},{""$reference"":""QUERY_ROOT.allProducts.1""},{""$reference"":""QUERY_ROOT.allProducts.2""}]}"
5	"QUERY_ROOT.allProducts.2"	"{""variation"":{""$reference"":""QUERY_ROOT.allProducts.2.variation""},""dimensions"":{""$reference"":""QUERY_ROOT.allProducts.2.dimensions""},""sku"":""client"",""id"":""apollo-client"",""__typename"":""Product""}"
6	"QUERY_ROOT.allProducts.1"	"{""variation"":{""$reference"":""QUERY_ROOT.allProducts.1.variation""},""dimensions"":{""$reference"":""QUERY_ROOT.allProducts.1.dimensions""},""sku"":""studio"",""id"":""apollo-studio"",""__typename"":""Product""}"
7	"QUERY_ROOT.allProducts.2.dimensions"	"{""__typename"":""ProductDimension"",""size"":""1""}"
8	"QUERY_ROOT.allProducts.2.variation"	"{""__typename"":""ProductVariation"",""id"":""OSS"",""name"":""client""}"
9	"QUERY_ROOT.allProducts.1.dimensions"	"{""__typename"":""ProductDimension"",""size"":""1""}"
10	"QUERY_ROOT.allProducts.0.dimensions"	"{""__typename"":""ProductDimension"",""size"":""1""}"
11	"QUERY_ROOT.allProducts.0"	"{""variation"":{""$reference"":""QUERY_ROOT.allProducts.0.variation""},""dimensions"":{""$reference"":""QUERY_ROOT.allProducts.0.dimensions""},""sku"":""federation"",""id"":""apollo-federation"",""__typename"":""Product""}"
12	"QUERY_ROOT.allProducts.1.variation"	"{""__typename"":""ProductVariation"",""id"":""platform"",""name"":""platform-name""}"
13	"QUERY_ROOT.allProducts.0.variation"	"{""__typename"":""ProductVariation"",""id"":""OSS"",""name"":""platform""}"

And here is cache data when using a custom cache key during incremental responses. Note how the incremental responses end up using the list index ("QUERY_ROOT.allProducts.X") as the key for the record instead of the custom cache key derived key. This incorrectly breaks the cache record into two parts and makes the incremental cache records irretrievable because they're not linked by "QUERY_ROOT".

"_id"	"key"	"record"
1	"Product:apollo-client"	"{""sku"":""client"",""__typename"":""Product"",""id"":""apollo-client""}"
2	"Product:apollo-federation"	"{""id"":""apollo-federation"",""sku"":""federation"",""__typename"":""Product""}"
3	"Product:apollo-studio"	"{""id"":""apollo-studio"",""sku"":""studio"",""__typename"":""Product""}"
4	"QUERY_ROOT"	"{""allProducts"":[{""$reference"":""Product:apollo-federation""},{""$reference"":""Product:apollo-studio""},{""$reference"":""Product:apollo-client""}]}"
5	"QUERY_ROOT.allProducts.0.dimensions"	"{""size"":""1"",""__typename"":""ProductDimension""}"
6	"QUERY_ROOT.allProducts.1"	"{""variation"":{""$reference"":""ProductVariation:platform""},""dimensions"":{""$reference"":""QUERY_ROOT.allProducts.1.dimensions""}}"
7	"ProductVariation:platform"	"{""id"":""platform"",""__typename"":""ProductVariation"",""name"":""platform-name""}"
8	"QUERY_ROOT.allProducts.2"	"{""variation"":{""$reference"":""ProductVariation:OSS""},""dimensions"":{""$reference"":""QUERY_ROOT.allProducts.2.dimensions""}}"
9	"ProductVariation:OSS"	"{""id"":""OSS"",""name"":""client"",""__typename"":""ProductVariation""}"
10	"QUERY_ROOT.allProducts.2.dimensions"	"{""size"":""1"",""__typename"":""ProductDimension""}"
11	"QUERY_ROOT.allProducts.1.dimensions"	"{""__typename"":""ProductDimension"",""size"":""1""}"
12	"QUERY_ROOT.allProducts.0"	"{""variation"":{""$reference"":""ProductVariation:OSS""},""dimensions"":{""$reference"":""QUERY_ROOT.allProducts.0.dimensions""}}"