Changing name GridData to custom

Hi All,

I am trying to upload multiple grid rows by using custom application.  When I tried with below format1 of jason file is working but when I change 'GridData' to 'forecast' its not working (before testing I have changed in orchestration grid text from GridData to forecast). My requirement is to use forecast instead of GridData as I am getting jason file as forecast.  Can you please suggest whats going wrong here?

format1:  working

{"GridData" : [ { "Item" : 828526,"RequestDate" : "2019/04/23","OrderType" : "WO","DemandSite" : "VARA","Quantity" : 1,"Supplier" : 1928 },

  {"Item" : 828527, "RequestDate" : "2019/04/23","OrderType" : "WO","DemandSite" : "VARA", "Quantity" : 2,"Supplier" : 1928}]}

Format2 : Not working

{"plannedorders" : [ { "Item" : 828526,"RequestDate" : "2019/04/23","OrderType" : "WO","DemandSite" : "VARA","Quantity" : 1,"Supplier" : 1928 },