Google Cloud Healthcare API search by date with time zone on FHIR resource returns error

I'm using Google Healthcare API and trying to search a FHIR resource by date with time zone, like example below:

https://healthcare.googleapis.com/v1/projects/project-id/locations/us-central1/datasets/dataset/fhirStores/fhirstore/fhir/Appointment?date=2020-01-23T08:29:00+03:00

And i'm getting this error:

{
    "issue": [
        {
            "code": "value",
            "details": {
                "text": "invalid_query"
            },
            "diagnostics": "error parsing date \"2020-01-23T08:29:00 03:00\": invalid dateTime: 2020-01-23T08:29:00 03:00",
            "severity": "error"
        }
    ],
    "resourceType": "OperationOutcome"
}

According to the documentation both FHIR and Google:

Date searches on any type of date, time, or period. The date parameter format is yyyy-mm-ddThh:mm:ss[Z|(+|-)hh:mm], and the same prefix modifiers used for number also apply here.

It should work, but when the timezone signal is "plus +". It throws an error. When is "minus -" ex: /Appointment?date=2020-01-23T08:29:00-03:00. it works.

Am I missing something? It looks like a bug to me.

Thanks!

Looks like a URL escaping issue - plus is one of the special characters in URLs.

Try date=2020-01-23T08:29:00%2B03:00, this works when I try it.