Object-level validation errors given an incorrect source.pointer

[arttuperala]

Description of the Bug Report

When raising a non-field ValidationError in a serializer in accordance with the DRF documentation, the error is attributed to a non-existing /data/attributes/non_field_errors path instead of /data.

from rest_framework_json_api import serializers

class ProductSerializer(serializers.ModelSerializer):
    def validate(self, data):
        if data.get("best_before_date") and data.get("expiry_date"):
            raise serializers.ValidationError(
                "Specify either a best before date or an expiry date."
            )
        return data

{
    "errors": [
        {
            "detail": "Specify either a best before date or an expiry date.",
            "status": "400",
            "source": {
                "pointer": "/data/attributes/non_field_errors"
            },
            "code": "invalid"
        }
    ]
}

Complete minimal example available here.

Discussed in #1135

Checklist

• Certain that this is a bug (if unsure or you have a question use discussions instead)
• Code snippet or unit test added to reproduce bug