Previously, the docregion code referenced a `nextId` variable that was
not shown in the code, which was confusing for the reader.
This commit makes the declaration of the `nextId` variable part of the
docregion, so it is clear to the reader where it comes from and how it
is initialized.
This commit also removes the `logIt()` helper method, which didn't seem
to add value and calls `logger.log()` directly instead.
PR Close#40208