StringOrListSerializer

A custom serializer for handling JSON values that can either be a single string or a list of strings. This serializer ensures that both formats are correctly deserialized into a List<String> and serialized back into their appropriate JSON representation.

This is particularly useful in cases where a JSON API may respond with a single string if there is only one value, or a list of strings if there are multiple values.

This serializer's behavior:

• During deserialization:

• If the value is a string, it converts it into a single-element list.

• If the value is an array of strings, it converts it into a list of strings.

• During serialization:

• If the list contains exactly one element, it serializes it as a single string.

• If the list size is not equal to 1 (including empty lists), it serializes it as a JSON array. Empty lists become empty JSON arrays [].

This serializer is compatible only with JSON encoding and decoding.

Throws:

• SerializationException if the serializer is used with a format other than JSON.

• SerializationException if the input during deserialization is neither a string nor an array of strings.