Cannot add or update project metadata by calling the swagger API directly

[zyyw]

If you are reporting a problem, please make sure the following information are provided:
Installing harbor oss v2.9.3, calling Harbor swagger API as below to update project metadata is failing:
request:

PUT /api/v2.0/projects/<project_id>/metadatas/public

payload:

{
    "public": "true"
}

Actual HTTP return message(it's an error):

{
    "errors": [
        {
            "code": "BAD_REQUEST",
            "message": "invalid key: "
        }
    ]
}

It also failed for adding a project metadata via POST:
request:

POST /projects/{project_name_or_id}/metadatas/

payload:

// some valid payload here

Actual HTTP return message (it's an error):

{
    "errors": [
        {
            "code": "BAD_REQUEST",
            "message": "invalid key: "
        }
    ]
}

Expected behavior and actual behavior:
The PUT request to update a project metadata and POST request to add a project metadata should working fine, instead of returning BAD_REQUEST.

Steps to reproduce the problem:
Install harbor v2.9.3, calling Harbor swagger API using curl/postman to send PUT or POST request, it will response with a BAD_REQUEST.

Versions:
Please specify the versions of following systems.

• harbor version: [v2.9.3] - v2.8.5 also has this issue
• docker engine version: [y.y.y]
• docker-compose version: [z.z.z]

Additional context:
This issue is due to this change in v2.9.3, and this change in v2.8.5.
This issue should be fixed in Harbor v2.9.4 and v2.8.6 (if there is a v2.8.6 patch release)
Workaround: using Harbor portal to configure your project metadata settings, instead of directly calling the Harbor swagger API to add or update project metadata.