form_field_groups is malformed when creating an embedded signature request

[ggggbbybby]

When I tried to send form_field_groups with my signature request, it would always throw this cryptic error:

{"error":{"error_msg":"'form_field_group' must have fields in 'form_fields_per_document'","error_path":"form_field_groups","error_name":"bad_request"}})

I wrote to apisupport@hellosign (support ticket #19005626) and they pointed out that the request payload was not formatted correctly.
I was passing this to create_embedded_signature_request

        [
          {
            group_id: "group_collections",
            group_label: "Collections",
            requirement: "require_1"
          },
          {
            group_id: "group_insurance",
            group_label: "Insurance",
            requirement: "require_1"
          },
          {
            group_id: "group_paymentplan",
            group_label: "PaymentPlan",
            requirement: "require_1"
          }
        ]

and this is how it was transformed to json

"form_field_groups": {
	"group_collections": [],
	"1": {
		"group_label": "C*** REDACTED [11 char]"
	},
	"2": {
		"requirement": "require_1"
	},
	"group_insurance": [],
	"4": {
		"group_label": "I*** REDACTED [9 char]"
	},
	"5": {
		"requirement": "require_1"
	},
	"group_paymentplan": [],
	"7": {
		"group_label": "P*** REDACTED [12 char]"
	},
	"8": {
		"requirement": "require_1"
	}
},

My fix was to wrap the array in MultiJson.dump(...) because that's how the other fields were transformed (prepare_signers etc). I realize that this is a legacy issue and easy to work around, but I wanted to make it visible for other people who might be running into the same issue.