{
  "lhs": {
    "anyOf": [
      {
        "type": "array",
        "items": [
          {"const": "start_unmerge"},
          {"type": "object"}
        ]
      }
    ]
  },
  "rhs": {
    "anyOf": [
      {
        "type": "array",
        "items": [
          {"const": "start_unmerge"},
          {"type": "object", "properties": {"transaction_id": {"type": "string"}}}
        ]
      }
    ]
  }
}