Convert JSON in schema.TypeString

Hello,

I have a parameter in my custom provider which is defined as below:

"local_context_data": {
    Type:     schema.TypeString,
    Optional: true,
},

This parameter is used to store JSON so in terraform code I use:

local_context_data = jsonencode({"hello"="world"})

But when I execute terraform I have the error message from the API:

Error: [POST /virtualization/virtual-machines/][400] virtualization_virtual-machines_create default map[local_context_data:[JSON data must be in object form. Example: {“foo”: 123}]]
on vm.tf line 73, in resource “netbox_virtualization_vm” “vm”:
73: resource “netbox_virtualization_vm” “vm” {

I can see with tcpdump that {“hello”=“world”} is sent to the API and not {“hello”=“world”}.
Do we have a function in the SDK to address this issue ? Or I need to do something in GO ?

Thanks.