Get item group list

{"groups": [{"children": [ ],
"description": "Accessory",
"external_id": "accessory",
"image_url": null,
"level": 0,
"name": "Accessory",
"order": 1,
"parent_external_id": null
},
{"children": [ ],
"description": "Background",
"external_id": "background",
"image_url": null,
"level": 0,
"name": "Background",
"order": 1,
"parent_external_id": null
},
{"children": [ ],
"description": "Hair",
"external_id": "hair",
"image_url": null,
"level": 0,
"name": "Hair",
"order": 1,
"parent_external_id": null
},
{"children": [ ],
"description": "Outfit",
"external_id": "outfit",
"image_url": null,
"level": 0,
"name": "Outfit",
"order": 1,
"parent_external_id": null
},
{"children": [ ],
"description": "Body",
"external_id": "body",
"image_url": null,
"level": 0,
"name": "Body",
"order": 1,
"parent_external_id": null
},
{"children": [ ],
"description": "Body",
"external_id": "delete_group",
"image_url": null,
"level": 0,
"name": "Body",
"order": 1,
"parent_external_id": null
},
{"children": [{"children": [ ],
"description": "Group description",
"external_id": "test_group_secure",
"image_url": "http://static.xsolla.com/img/xsolla-logo2.png",
"level": 1,
"name": "Test group secure",
"order": 5,
"parent_external_id": "very_cool_group"
}
],
"description": "Very cool group",
"external_id": "very_cool_group",
"image_url": null,
"level": 0,
"name": "Very cool group",
"order": 1,
"parent_external_id": null
},
{"children": [{"children": [ ],
"description": "Group description",
"external_id": "test_group_split",
"image_url": "http://static.xsolla.com/img/xsolla-logo2.png",
"level": 1,
"name": "Test group secure",
"order": 1,
"parent_external_id": "test_group_secure"
}
],
"description": "Group description",
"external_id": "test_group_secure",
"image_url": "http://static.xsolla.com/img/xsolla-logo2.png",
"level": 0,
"name": "Test group secure",
"order": 1,
"parent_external_id": null
}
]
}