missing credentials.json

[ajataval]

I tried to download and run this application. Followed all steps. After inserting "client_id" and "client_secret". I ran the application for first time and it gave error as below.
/usr/local/lib/python2.7/dist-packages/oauth2client/_helpers.py:255: UserWarning: Cannot access credentials.json: No such file or directory
warnings.warn(_MISSING_FILE_MESSAGE.format(filename))
usage: chunked_transfer.py [--auth_host_name AUTH_HOST_NAME]
[--noauth_local_webserver]
[--auth_host_port [AUTH_HOST_PORT [AUTH_HOST_PORT ...]]]
[--logging_level {DEBUG,INFO,WARNING,ERROR,CRITICAL}]
chunked_transfer.py: error: unrecognized arguments: Downloads/file gs://twenty20-dump/file

I know it should run for the first time and generate the file, but it is giving this error.

[bileki]

You have to create a empty file credentials.json

[DamienLopvet]

for google calendar API it was not enougth to create an empty file but I had to fill it with the credentials file in json format from OAuth 2.0 Client IDs google cloud console