Upgrade to Java API Client

Hey guys.

We are currently upgrading our ES in production from 7.16.1 to 7.17.7. This is a must for us, client's requirement leaves us no option but to upgrade to this version. Now having moved to 7.17.7 we were wondering about the RestHighLevelClient. It is deprecated, so we should probably move to Java Client.

Also our client is having problems with this log that is exhausting CPU a lot -> "[ignore_throttled] parameter is deprecated because frozen indices have been deprecated. Consider cold or frozen tiers in place of frozen indices." Seems like this log is present if you are using RestHighLevelClient, whic is deprecated.

Q1: Is there a way to disable this log? Migration might take us some time, we would like to get rid of this warning until then.

Q2: Is it ok if we do not migrate at all and stay with the deprecated client? I'm sorry to say, but It seems like the documentation of the new client is rather poor, and our system is large and high traffic. Major share of it's business logic dependes on Elasticsearch operations, we cannot go for it without reliable documentation of the API, hence I would like to now the pitfalls of staying with the deprecated version.

Small update.

Q3: Is it fine to migrate not everything at once by step by step in batches? Does it make sense?