What is the best way to return a formatted data structure (like option_1.txt or option_2.txt) from the initial flat data structure (initial_flat_structure.txt) using Clojure?

clojure_structure.txt

(def initial_data [
  { :entry "E1", :judge "J1", :comment "E1J1C1" },
  { :entry "E1", :judge "J2", :comment "E1J2C1" },
  { :entry "E1", :judge "J1", :comment "E1J1C2" },
  { :entry "E2", :judge "J1", :comment "" },
  { :entry "E2", :judge "J2", :comment "" },
  { :entry "E3", :judge "J1", :comment "E3J1C1" },
  { :entry "E3", :judge "J1", :comment "E3J1C2" },
  { :entry "E3", :judge "J2", :comment "" }
])

initial_flat_structure.txt

[
  { "entry":"Entry 1", "judge":"John", "comment":"Entry 1 Comment 1 John" },
  { "entry":"Entry 1", "judge":"Alison", "comment":"Entry 1 Comment 1 Alison" },
  { "entry":"Entry 1", "judge":"John", "comment":"Entry 1 Comment 2 John" },
  { "entry":"Entry 2", "judge":"John", "comment":"" },
  { "entry":"Entry 2", "judge":"Alison", "comment":"" },
  { "entry":"Entry 3", "judge":"John", "comment":"Entry 3 Comment 1 John" },
  { "entry":"Entry 3", "judge":"John", "comment":"Entry 3 Comment 2 John" },
  { "entry":"Entry 3", "judge":"Alison", "comment":"" }
]

option_1.txt

[
  {
    "entry":"Entry 1",
    "judge":"John",
    "comments":[
      "Entry 1 Comment 1 John",
      "Entry 1 Comment 2 John"
    ]
  },
  {
    "entry":"Entry 1",
    "judge":"Alison",
    "comments":[
      "Entry 1 Comment 1 Alison"
    ]
  },
  {
    "entry":"Entry 2",
    "judge":"John",
    "comments":[]
  },
  {
    "entry":"Entry 2",
    "judge":"Alison",
    "comments":[]
  },
  {
    "entry":"Entry 3",
    "judge":"John",
    "comments":[
      "Entry 3 Comment 1 John",
      "Entry 3 Comment 2 John"
    ]
  },
  {
    "entry":"Entry 3",
    "judge":"Alison",
    "comments":[]
  }
]

option_2.txt

[
  {
    "entry":"Entry 1",
    "judges":[
      "John":{
        "comments":[
          "Entry 1 Comment 1 John",
          "Entry 1 Comment 2 John"
        ]
      },
      "Alison":{
        "comments":[
          "Entry 1 Comment 1 Alison"
        ]
      }
    ]
  },
  {
    "entry":"Entry 2",
    "judges":[
      "John":{
        "comments":[] 
      },
      "Alison":{
        "comments":[]
      }
    ]
  },
  {
    "entry":"Entry 3",
    "judges":[
      "John":{
        "comments":[
          "Entry 3 Comment 1 John",
          "Entry 3 Comment 2 John"
        ]
      },
      "Alison":{
        "comments":[]
      }
    ]
  }
]