Why is Wiremock Standalone rejecting my valid JSONPath expression? - arrays

Question

Background
I am using wiremock-jre8-standalone-2.35.0.jar
I want it to return a 200 response if the incoming request's array contains any values:
{
"field1": "data1",
"array": [
{...},
{...},
...
],
"field2": "data2",
"field3": "data3",
"field4": "data4",
"field5": "data5"
}
I want it to return a 400 response if the incoming requests' array is empty:
{
"field1": "data1",
"array": [],
"field2": "data2",
"field3": "data3",
"field4": "data4",
"field5": "data5"
}
Wiremock should match the incoming request against the "request": {...} from the below code:
{
"id": "...",
"request": {
"urlPattern": "...",
"method": "POST",
"headers": {...},
"bodyPatterns": [
{
"matchesJsonPath": "$[?(#.length < 1)]"
}
]
}
},
"response": {
"status": 400,
"bodyFileName": "...",
"headers": {...}
},
"uuid": "..."
}
Problem
Wiremock is rejecting my JSONPath expression in the bodyPatterns array:
[{"matchesJsonPath":"$[?(#.length < 1)]"}] is not a valid match operation
Yet it seems that the expression is valid according to https://jsonpath.com/ :
JSONPath
---
$[?(#.length < 1)]
Inputs
---
{
"field1": "data1",
"array": [],
"field2": "data2",
"field3": "data3",
"field4": "data4",
"field5": "data5"
}
Evaluation Results
---
[
[]
]
...What gives?

Answer 1

This is what gives:
JSON Path
Deems a match if the attribute value is valid JSON and matches the JSON Path expression supplied. A JSON body will be considered to match a path expression if the expression returns either a non-null single value (string, integer etc.), or a non-empty object or array.
https://wiremock.org/docs/request-matching/
My JSON Path expression returns an empty array, so it cannot be considered to match the path expression.