How can I attach a header to the column without it

I have this dataset

_id: 654e312d4ff391e4ef2244ad
Id: 2
SepalLengthCm: 4.9
:3
PetalLengthCm: 1.4
PetalWidthCm: 0.2
Species: "Iris-setosa"

and mongodb recognize like this,

{
  "Id": 2,
  "SepalLengthCm": 4.9,
  "PetalLengthCm": 1.4,
  "PetalWidthCm": 0.2,
  "Species": "Iris-setosa"
}

him ignore de “:3”, despite save them.

I tried rename, but doesn’t work because isn’t recognized “” by the mongo. something like:

db.collection.updateMany({}, { $rename: { "": "tmpName" } });
db.collection.updateMany({}, { $rename: { " ": "tmpName" } });
db.collection.updateMany({' ':3}, { $rename: { ' ': 'tmpName' } });
db.collection.updateMany({"",{$exists, true}}, { $rename: { "": "tmpName" } });

and similars …

I need put a header in “:3”

{
  "Id": 2,
  "SepalLengthCm": 4.9,
  "tmpName":3,
  "PetalLengthCm": 1.4,
  "PetalWidthCm": 0.2,
  "Species": "Iris-setosa"
}

that’s the idea, I need to import a csv without 1 header and I want to fix them. And mongo saves like this.