JOLT Transform from flat repeating to nested array

[#1]

I'm trying to transform flat repeating values from flat JSON to nested Array.In the below is a sample, there are IN1_1 and IN1_2 repeating values. The numeric being the index. I've tried a number of different JOLT specs, but can't seem to get it right.

{
"IN1_1.NameOfInsured.DegreeEgMD": "MME",
"IN1_2.NameOfInsured.FamilyName": "SEIBERT",
"IN1_1.NameOfInsured.GivenName": "GALE",
"IN1_2.InsuredsRelationshipToPatient.Identifier": "SELF",
"IN1_2.InsurancePlanID.Identifier": "Medicare",
"IN1_1.NameOfInsured.SecondAndFurtherGivenNamesOrInitialsThereof": "MATTHEW",
"IN1_2.NameOfInsured.SecondAndFurtherGivenNamesOrInitialsThereof": "MATTHEW",
"IN1_2.SetIDIN1": "2",
"IN1_2.NameOfInsured.DegreeEgMD": "MME",
"IN1_1.NameOfInsured.FamilyName": "SEIBERT",
"IN1_1.InsuredsRelationshipToPatient.Identifier": "SELF",
"IN1_2.NameOfInsured.GivenName": "GALE",
"IN1_1.SetIDIN1": "1",
"IN1_1.InsurancePlanID.Identifier": "UNIT HLTH"
}

Desired output

{
	"Insurance":[
	{
		"IN1_1.SetIDIN1": "1",
		"IN1_1.InsurancePlanID.Identifier": "UNIT HLTH",
		"IN1_1.InsuredsRelationshipToPatient.Identifier": "SELF",
		"IN1_1.NameOfInsured.SecondAndFurtherGivenNamesOrInitialsThereof": "MATTHEW",
		"IN1_1.NameOfInsured.GivenName": "GALE",
		"IN1_1.NameOfInsured.FamilyName": "SEIBERT",
		"IN1_1.NameOfInsured.DegreeEgMD": "MME"
	 },
	 {
		"IN1_2.SetIDIN1": "2",
		"IN1_2.InsurancePlanID.Identifier": "Medicare",
		"IN1_2.InsuredsRelationshipToPatient.Identifier": "SELF",
		"IN1_2.NameOfInsured.SecondAndFurtherGivenNamesOrInitialsThereof": "MATTHEW",
		"IN1_2.NameOfInsured.GivenName": "GALE",
		"IN1_2.NameOfInsured.FamilyName": "SEIBERT",
		"IN1_2.NameOfInsured.DegreeEgMD": "MME"
	}
	]
}

[#2]

I've gotten a little closer using pivots, but now i want to remove the pivot values that make the nested arrays.... My spec:

[
  {
    //split IN1.* and pivot to key value pairs
    "operation": "shift",
    "spec": {
      "IN1_*.*": {
        "$(0,1)": "pivoted.&1.key1",
        "$(0,2)": "pivoted.&1.key2",
        "@": "pivoted.&1.value"
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "pivoted": {
        "*": {
          "value": "@(1,key1).@(1,key2)"
        }
      }
    }
  }
]

New output:

{
  "1" : {
    "SetIDIN1" : "1",
    "InsurancePlanID.Identifier" : "UNIT HLTH",
    "InsuredsRelationshipToPatient.Identifier" : "SELF",
    "NameOfInsured.SecondAndFurtherGivenNamesOrInitialsThereof" : "MATTHEW",
    "NameOfInsured.GivenName" : "GALE",
    "NameOfInsured.FamilyName" : "SEIBERT",
    "NameOfInsured.DegreeEgMD" : "MME"
  },
  "2" : {
    "SetIDIN1" : "2",
    "InsurancePlanID.Identifier" : "Medicare",
    "InsuredsRelationshipToPatient.Identifier" : "SELF",
    "NameOfInsured.SecondAndFurtherGivenNamesOrInitialsThereof" : "MATTHEW",
    "NameOfInsured.GivenName" : "GALE",
    "NameOfInsured.FamilyName" : "SEIBERT",
    "NameOfInsured.DegreeEgMD" : "MME"
  }
}

Desired output:

{
	"Insurance":[
	{
		"IN1_1.SetIDIN1": "1",
		"IN1_1.InsurancePlanID.Identifier": "UNIT HLTH",
		"IN1_1.InsuredsRelationshipToPatient.Identifier": "SELF",
		"IN1_1.NameOfInsured.SecondAndFurtherGivenNamesOrInitialsThereof": "MATTHEW",
		"IN1_1.NameOfInsured.GivenName": "GALE",
		"IN1_1.NameOfInsured.FamilyName": "SEIBERT",
		"IN1_1.NameOfInsured.DegreeEgMD": "MME"
	 },
	 {
		"IN1_2.SetIDIN1": "2",
		"IN1_2.InsurancePlanID.Identifier": "Medicare",
		"IN1_2.InsuredsRelationshipToPatient.Identifier": "SELF",
		"IN1_2.NameOfInsured.SecondAndFurtherGivenNamesOrInitialsThereof": "MATTHEW",
		"IN1_2.NameOfInsured.GivenName": "GALE",
		"IN1_2.NameOfInsured.FamilyName": "SEIBERT",
		"IN1_2.NameOfInsured.DegreeEgMD": "MME"
	}
	]
}