Re-posting the last inquiry (https://groups.google.com/g/adwords-api/c/Xx0GN5thQwQ) from the forum as it wasn't routed to our support queue.
Regards,
Google Ads API Team
Thanks for reaching out to the Google Ads API Team. I hope you are doing well today.
I understand your concern, as this matter is as important to us as it is to you. However, the “generated historical metrics call KeywordPlanIdeaService.GenerateKeywordHistoricalMetrics” sample code for client libraries are not yet available on our Google Ads API documentation. In line with this, since your question is more on code related for client libraries, I would suggest to reach out to the author of this client library that you want to use via github (https://developers.google.com/google-ads/api/docs/client-libs) issues tracker as they can provide helpful solution here or accurate recommendations.
Have a great day.
Regards,
Google Ads API Team