How to ser Ltree array set php?

REQUEST

$array = [
   [
    "hierarchy" => "1",
   ],
   [
    "hierarchy" => "1.1",
   ],
   [
    "hierarchy" => "1.1.1",
   ],
   [
    "hierarchy" => "1.1.2",
   ],
   [
    "hierarchy" => "1.2",
   ],
   [
    "hierarchy" => "1.2.1",
   ],
   [
    "hierarchy" => "1.2.2",
   ],
   [
    "hierarchy" => "2",
   ],
   [
    "hierarchy" => "2.1",
   ],
   [
    "hierarchy" => "2.2",
   ],
   [
    "hierarchy" => "3.1.1",
   ],
   [
    "hierarchy" => "3.1.1.1",
   ]
];

I WANT THIS TYPE OF RESPONSE

[
  {
    "hierarchy": "1",
    "children": [
      {
        "hierarchy": "1.1",
        "children": [
          {
            "hierarchy": "1.1.1"
          },
          {
            "hierarchy": "1.1.2"
          }
        ]
      },
      {
        "hierarchy": "1.2",
         "children": [
          {
            "hierarchy": "1.2.1"
          },
          {
            "hierarchy": "1.2.2"
          }
        ]
      }
    ],
    "hierarchy": "2",
    "children": [
      {
        "hierarchy": "2.1"
      },
      {
        "hierarchy": "2.2"
      }
    ],
    "hierarchy": "3.1.1",
    "children": [
      {
        "hierarchy": "3.1.1",
      }
        ]
      },
  }
]