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CLAs look good, thanks!

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Just adding some more context:
The way it is now, the constructor will always get an empty object/dict.
If I change the name of the configuration in googleads.yaml from report_downloader_headers to report_download_headers it will throw a warning: UserWarning: Could not recognize the following keys: {'report_download_headers':...} because it is not listed in _OPTIONAL_INIT_VALUES