The changes related to APIs are as follows:
- The internal versioning support for optimistic concurrency control is eliminated.
- In the document bulk API, use the retry_on_conflict parameter instead of _retry_on_conflict; use routing instead of _routing; use version instead of _version; and use version_type instead of _version_type. Use the join meta-field instead of the _parent in mapping. All previous underscore parameters are eliminated. The camel-case parameters such as opType, versionType, and _versionType have been eliminated.
- The cat thread pool API has renamed some field names from 6.x to 7.0 to align the meaning in the fixed thread pools and scaling thread pools. Use pool_size instead of the original size and core instead ...