No longer true. 
For Ignition v8.1+: v2.0.3.231942018
With @Matthew.gaitan 's input dataset in a custom property named source, this expression:
forEach(
asMap(
groupBy(
{this.custom.source},
it()['RouteName'],
it()['StopName']
)
),
asMap(
'label', it()[0],
'expanded', false,
'data', asMap('nodeType', 'Route'),
'items', forEach(
it()[1],
asMap(
'label', it()[0],
'expanded', false,
'data', asMap('nodeType', 'Stop'),
'items', forEach(
it()[1],
asMap(
'label', it()['WellName'],
'expanded', false,
'data', asMap('nodeType', 'Well'),
'items', asList()
)
)
)
)
)
)
Yields this output:
[
{
"label": "Route 1",
"expanded": true,
"data": {
"nodeType": "Route"
},
"items": [
{
"label": "Stop 1",
"expanded": false,
"data": {
"nodeType": "Stop"
},
"items": [
{
"label": "Well 1",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 2",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 3",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 4",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 5",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 6",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 7",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 8",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 9",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
}
]
},
{
"label": "Stop 2",
"expanded": false,
"data": {
"nodeType": "Stop"
},
"items": [
{
"label": "Well 1",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 2",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 3",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 4",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 5",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 6",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 7",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
}
]
}
]
},
{
"label": "Route 2",
"expanded": true,
"data": {
"nodeType": "Route"
},
"items": [
{
"label": "Stop 1",
"expanded": false,
"data": {
"nodeType": "Stop"
},
"items": [
{
"label": "Well 1",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 2",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 3",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 4",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 5",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 6",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 7",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
}
]
},
{
"label": "Stop 2",
"expanded": true,
"data": {
"nodeType": "Stop"
},
"items": [
{
"label": "Well 1",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 2",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 3",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 4",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 5",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 6",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 7",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 8",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
}
]
},
{
"label": "Stop 3",
"expanded": false,
"data": {
"nodeType": "Stop"
},
"items": [
{
"label": "Well 1",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 2",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 3",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 4",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 5",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 6",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 7",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 8",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 9",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
}
]
},
{
"label": "Stop 4",
"expanded": true,
"data": {
"nodeType": "Stop"
},
"items": [
{
"label": "Well 1",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 2",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 3",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 4",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 5",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
}
]
}
]
},
{
"label": "Route 3",
"expanded": true,
"data": {
"nodeType": "Route"
},
"items": [
{
"label": "Stop 1",
"expanded": false,
"data": {
"nodeType": "Stop"
},
"items": [
{
"label": "Well 1",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 2",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 3",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 4",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 5",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 6",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 7",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
}
]
},
{
"label": "Stop 2",
"expanded": false,
"data": {
"nodeType": "Stop"
},
"items": [
{
"label": "Well 1",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 2",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 3",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 4",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 5",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 6",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 7",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 8",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 9",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 10",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
}
]
},
{
"label": "Stop 3",
"expanded": false,
"data": {
"nodeType": "Stop"
},
"items": [
{
"label": "Well 1",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 2",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 3",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 4",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 5",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 6",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 7",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 8",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
},
{
"label": "Well 9",
"expanded": false,
"data": {
"nodeType": "Well"
},
"items": []
}
]
}
]
}
]
The magic is here:
https://www.automation-pros.com/simaids/doc/expression.groupby.html
The asMap() function was altered to handle multi-item keys in a sequence of key-value pairs as requests to make nested mappings. Note that the asMap function will work with key values that are not valid names within Perspective objects, so you may need to construct such maps nested in the expression that consumes them (as in this case).
Both asMap() and asList() were updated to properly return an empty object when given no arguments.