Scopes not configured for service account error

This error occurs to me when I try to use default credentials created from the GOOGLE_APPLICATION_CREDENTIALS variable. This is the error I get whenever I try to issue a request:

java.io.IOException: Scopes not configured for service account. Scoped should be specifed by calling createScoped or passing scopes to constructor.
    at com.google.auth.oauth2.ServiceAccountCredentials.refreshAccessToken(ServiceAccountCredentials.java:183)
    at com.google.auth.oauth2.OAuth2Credentials.refresh(OAuth2Credentials.java:76)
    at com.google.auth.oauth2.OAuth2Credentials.getRequestMetadata(OAuth2Credentials.java:53)
    at com.google.auth.http.HttpCredentialsAdapter.initialize(HttpCredentialsAdapter.java:40)
    at com.google.gcloud.ServiceOptions$1.initialize(ServiceOptions.java:510)
    at com.google.api.client.http.HttpRequestFactory.buildRequest(HttpRequestFactory.java:93)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.buildHttpRequest(AbstractGoogleClientRequest.java:300)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:419)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:352)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:469)
    at com.google.gcloud.spi.DefaultStorageRpc.list(DefaultStorageRpc.java:148)

It seems that to create default credentials based on the env variable we must supply the service scopes. This can be done by changing this line to:

GoogleCredentials.getApplicationDefault().createScoped(scopes);

This would require, however, to change our AuthCredentials.createApplicationDefaults method to accept a set of scopes as a parameter.

Noticeably, scopes are not required to be passed when Google Cloud SDK credentials are used. Is this a desired behavior of the auth library? Should we add this scopes parameter?