sendMail method Null safety

dynamic sendMail(
  1. String contactEmail,
  2. String contactName,
  3. String subject,
  4. String message
)

Implementation

sendMail(String contactEmail, String contactName, String subject,
    String message) async {
  LiquidHTTPCaller _httpCaller = LiquidHTTPCaller();

  _httpCaller.postData('https://api.liquidsoft.io/SendGrid/', {
    "personalizations": [
      {
        "to": [
          {
            'email': contactEmail,
            'name': contactName,
          }
        ],
        "subject": subject,
      }
    ],
    "from": {
      "email": "mailer@liquidsoft.io",
      'name': "Customer Service",
    },
    "reply_to": {
      "email": "chris@liquidsoft.io",
      'name': "Customer Service",
    },
    "content": [
      {
        "type": "text/html",
        "value": message,
      }
    ]
  });
}