Google Fit REST API - dataStreamId with whitespace results in error - rest

Question

I want to use Google's REST API to get the Fitness data of my account. To do so i issue 2 subsequent calls.
GET https://www.googleapis.com/fitness/v1/users/me/dataSources. This returns a list of all available dataSources as in [1].
POST https://www.googleapis.com/fitness/v1/users/me/dataset:aggregate.
I use the dataType name and dataStreamId in the request body from [1] to build the request body [2].
The problem: The second call returns an error [3] for all dataSourceIds that contain whitespace although they were returned exactly that way in the first request. In the code sample there is whitespace because the dataSourceId contains the phone model "Nexus 5". If there is no whitespace, the request succeeds without errors.
I already tried replacing the space by something else ("%20" or "_" or "+") but nothing helped. Is this a bug in the API or am i doing something fundamentally wrong?
Thanks in advance!
Edit 1:
btw i am using Google's oauth-playground with all the fitness scopes selected.
https://developers.google.com/oauthplayground/
Edit 2:
In code sample [2] i used the wrong dataTypeName. Was "activity_confidence" but should be "com.google.activity.samples".
[1] GET response
{
"dataSource": [
{
"application": {
"packageName": "com.google.android.gms"
},
"dataQualityStandard": [
],
"dataStreamId": "derived:com.google.activity.samples:com.google.android.gms:LGE:Nexus 5:c80045fc:detailed",
"dataStreamName": "detailed",
"dataType": {
"field": [
{
"format": "map",
"name": "activity_confidence"
}
],
"name": "com.google.activity.samples"
},
"device": {...},
"type": "derived"
},
...
]
}
[2] POST body
{
"aggregateBy": [
{
"dataSourceId": "derived:com.google.activity.samples:com.google.android.gms:LGE:Nexus 5:c80045fc:detailed",
"dataTypeName": "com.google.activity.samples"
}
],
"endTimeMillis": 1511132400000,
"startTimeMillis": 1510268400000
}
[3] POST Error message
{
"error": {
"code": 400,
"errors": [
{
"domain": "global",
"message": "datasource not found: derived:com.google.activity.samples:com.google.android.gms:LGE:Nexus 5:c80045fc:detailed",
"reason": "invalidArgument"
}
],
"message": "datasource not found: derived:com.google.activity.samples:com.google.android.gms:LGE:Nexus 5:c80045fc:detailed"
}
}

Answer 1

Did you try using a escape character like '\'?
Your data stream ID would look like
derived:com.google.activity.samples:com.google.android.gms:LGE:Nexus\ 5:c80045fc:detailed