In jOOQ 3.15, the public org.jooq.tools.Convert utility got copied into the internal org.jooq.impl.Convert utility:
The approach chosen was copying the implementation and unit tests, until the deprecated public utility can be removed. This has proven very tedious to maintain as the utility had way more issues than I expected, especially with timestamp related conversions.
As such, it will be more maintainable to delegate instead of copying. We'll route all calls via new org.jooq.impl.Internal API, in order to give access to package private org.jooq.impl.Convert API.