A serializer mixin to handle advanced pacing fields for the Bidding model.

This mixin dynamically adjusts the serializer's behavior based on the state of the
ENABLE_PACEMAKER_V2 feature flag and the pacing configuration of the bidding instance.

• If Pacemaker V2 is disabled, advanced pacing fields are removed from the serialized output.
• If Pacemaker V2 is enabled or if the bidding.pacing attribute requires processing, default
  values are applied to pacing-related fields when they are not already set.

Convenience mixin to deserialize nullable nested JSON objects to root
fields of a line item.

Implement get_default in mixed-in class. If a null is passed we need to
set internal value to a default value for all fields included in the nested
serializer.

Convenience mixin to deserialize nullable nested JSON objects to root
fields of a line item.

Implement get_default in mixed-in class. If a null is passed we need to
set internal value to a default value for all fields included in the nested
serializer.

Convenience mixin to deserialize nullable nested JSON objects to root
fields of a line item.

Implement get_default in mixed-in class. If a null is passed we need to
set internal value to a default value for all fields included in the nested
serializer.

Convenience mixin to deserialize nullable nested JSON objects to root
fields of a line item.

Implement get_default in mixed-in class. If a null is passed we need to
set internal value to a default value for all fields included in the nested
serializer.

The list of the vendor fees objects.

The list of flights with an end date greater than the current time.

Convenience mixin to deserialize nullable nested JSON objects to root
fields of a line item.

Implement get_default in mixed-in class. If a null is passed we need to
set internal value to a default value for all fields included in the nested
serializer.

The list of the unique identifiers representing the associated events.

A mixin that should be inherited by a custom serializer to include the logic for validating warnings.

This mixin works by recursively descending into nested levels of the root serializer,
collecting warnings in a dictionary structure, and raising them at a higher level.

To implement warnings in a custom serializer, two types of methods must be used.
The first type is used to handle field errors: warn_<field name>().
The second type is used for non-field warnings: warn().

Usage:
class NestedSerializer(WarningsSerializerMixin, serializers.Serializer):
baz = serializers.IntegerField()

    def warn_baz(self, value):
        ...

    def warn(self, attrs):
        ....

class RootSerializer(WarningsSerializerMixin, serializers.Serializer):
    foo = NestedSerializer()
    bar = serializers.CharField()

    def warn_bar(self, value):
        ...

    def warn(self, attrs):
        ...

Convenience mixin to deserialize nullable nested JSON objects to root
fields of a line item.

Implement get_default in mixed-in class. If a null is passed we need to
set internal value to a default value for all fields included in the nested
serializer.