Retrieving all of a Project Categories

{
  "categories": [
    {
      "parent-id": "",
      "name": "Information",
      "count": "3",
      "elements-count": "3",
      "id": "1",
      "color": "A94136",
      "type": "ProjectCategory"
    },
    {
      "parent-id": "1",
      "name": "Features",
      "count": "2",
      "elements-count": "2",
      "id": "1",
      "color": "0AD2F5",
      "type": "ProjectCategory"
    },
    {
      "parent-id": "",
      "name": "",
      "count": "3",
      "elements-count": "3",
      "id": "",
      "color": "F1C40F",
      "type": "ProjectCategory"
    },
    {
      "parent-id": "",
      "name": "Other",
      "count": "1",
      "elements-count": "1",
      "id": "",
      "color": "D870AD",
      "type": "ProjectCategory"
    }
  ]
}