Terraform import doesn't import visualisation workbook configuration

[denisovval]

Issue Description

When executing the terraform import command for the doublecloud_workbook resource, the import is successful. However, the Terraform state file contains null values in the config and connect attributes, which is unexpected. Here is the command used and the resulting state:

Command Used:

terraform import doublecloud_workbook.workbook_name <workbook_id>

"instances": [
    {
        "schema_version": 0,
        "attributes": {
            "config": null,
            "connect": [],
            "id": "<workbook_id>",
            "project_id": null,
            "title": null
        }
    }
]

Expected Behavior

The expected behaviour is that after importing the doublecloud_workbook resource, the config and connect attributes (along with project_id and title) should contain the appropriate values rather than null or empty lists.

Environment

•	Terraform version:  1.8.5
•	Terraform provider version: 0.1.23
•	DoubleCloud resource type: doublecloud_workbook