Message with &aa part in green and &ca part in red

Message with §aa part in green and §ca part in red

[
  {
    "text": "",
    "extra": [
      "Message with ",
      {
        "text": "a part in green and ",
        "color": "green"
      },
      {
        "text": "a part in red",
        "color": "red"
      }
    ]
  }
]