Workflow:

{
    "nodes": [
        {
            "name": "Mock Data",
            "type": "n8n-nodes-base.function",
            "position": [
                550,
                300
            ],
            "parameters": {
                "functionCode": "return [{json:[\"item-1\", \"item-2\", \"item-3\", \"item-4\"]}];"
            },
            "typeVersion": 1
        },
        {
            "name": "Function",
            "type": "n8n-nodes-base.function",
            "position": [
                750,
                300
            ],
            "parameters": {
                "functionCode": "return items[0].json.map(item => {\n  return {\n    json: {\n      data:item\n    },\n  }\n});\n"
            },
            "typeVersion": 1
        }
    ],
    "connections": {
        "Mock Data": {
            "main": [
                [
                    {
                        "node": "Function",
                        "type": "main",
                        "index": 0
                    }
                ]
            ]
        }
    }
}