An array of values can be validated using listPath key.
Validation Result:
valid

Current Rules
[
{
"path": "listChild",
"ruleSet": [
"required",
{
"rule": "listSize",
"greaterThan": 2
}
]
},
{
"listPath": "listChild",
"ruleSet": [
"required",
{
"rule": "length",
"greaterThan": 3
}
]
}
]