[DAR-3919][External] Warn when importing annotations with multiple instance IDs

[JBWilkie]

Problem

With the release of static instance IDs, if uploading an annotation with multiple instance IDs - Only the value of the instance ID on the first keyframe is used for import

This may confuse users who expect static instance IDs to operate like dynamic instance IDs, which is the current behaviour

Solution

If the static instance IDs feature flag is present & enabled, OR if the flag doesn't exist, we perform the following check: For each frame of every video annotation check sub-annotations. If there is >1 unique instance ID value in any annotation, record this

After checking all annotations, print a warning for each affected file as follows:

The following files have annotation(s) with multiple instance ID values. Instance IDs are static, so only the first instance ID of each annotation will be imported::
- File: {local_annotation_file_path_1} has {n_1} annotation(s) with multiple instance IDs
- File: {local_annotation_file_path_2} has {n_2} annotation(s) with multiple instance IDs

We check if the flag is present so that the code will still work when the flag is deprecated in the future. From this point onward, we will always perform the check

Changelog

Added a warning when importing annotations with multiple instance ID values where only 1 value will be imported due to static instance IDs

[linear]

DAR-3919 Add a warning when uploading instance IDs with >1 value

[dorfmanrobert]

why do we need this static_instance_id_feature_flag_exists and associated check? it exists, so seems this is unneeded

[JBWilkie]

We only want to run the validation that this PR introduces (_warn_for_annotations_with_multiple_instance_ids) if:

• 1: The STATIC_INSTANCE_ID feature flag exists and it's value for the target workspace is True, or:
• 2: The flag doesn't exist. At this point, the feature will be globally enabled so we will always want to run the check. We'll be able to remove this section of code (apart from the function call to _warn_for_annotations_with_multiple_instance_ids, but the flag will be removed before we can update darwin-py

[dorfmanrobert]

oooh makes sense thanks!