Can a Swift user account be created without creating an S3 account, in RHCS Rados Gateway?

Issue

• By default, a Swift user account comes under a S3 user account.

• For example, the Swift user "swift-user2" exists as a subuser to the S3 user account "S3user2", in the following example.

# radosgw-admin user info --uid=S3user2
{
    "user_id": "S3user2",
    "display_name": "S3user2",
    "email": "",
    "suspended": 0,
    "max_buckets": 1000,
    "auid": 0,
    "subusers": [
        {
            "id": "S3user2:swift-user2",
            "permissions": "<none>"
        }
    ],
    "keys": [
        {
            "user": "S3user2:swift-user2",
            "access_key": "BFTUX19XXY5CDB1ZVNXU",
            "secret_key": ""
        },
        {
            "user": "S3user2",
            "access_key": "BX4JB3A47AFIBB017MQZ",
            "secret_key": "cE4vySnPEH0dQ82Y0t5BQ\/9ke4STV0W2H9bez0DR"
        }
    ],
    "swift_keys": [],
    "caps": [],
    "op_mask": "read, write, delete",
    "default_placement": "",
    "placement_tags": [],
    "bucket_quota": {
        "enabled": false,
        "max_size_kb": -1,
        "max_objects": -1
    },
    "user_quota": {
        "enabled": false,
        "max_size_kb": -1,
        "max_objects": -1
    },
    "temp_url_keys": []
}

• Are there any ways to create a Swift user account without creating or nesting it under an S3 account?