Description

I've found it hard to build observability on logically-dropped events (either due to transform, null, or temporal conditions).
This adds:

• Better logging in task logs indicating the breakdown of thrown away events by reason.
• A reason dimension to the ingest/events/thrownAway metric for aggregating on thrown away reason.
• A thrownAwayByReason map to row statistics task API response payload, so future consumers can make use of it should they need to.
• Better interface for row filters, making it easy to adding more filtering reasons in the future.

Release note

Add reason dimension to ingest/events/thrownAway metric. This allows for increased observability on why certain events are being logically excluded from ingest.

This PR has:

• been self-reviewed.
  • using the concurrency checklist (Remove this item if the PR doesn't have any relation to concurrency.)
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.