query ListContactMatches {
  listContactMatches {
    contactId
    firstName
    lastName
    email
    phoneNumber
    duplicateOfContactId
  }
}

{
  "data": {
    "listContactMatches": [
      {
        "contactId": "id",
        "firstName": "string",
        "lastName": "string",
        "email": "string",
        "phoneNumber": "string",
        "duplicateOfContactId": "id"
      }
    ]
  }
}