JsonIgnoreCondition
Controls how the JsonIgnoreAttribute ignores properties on serialization and deserialization.
Always = 1
Property is always ignored.
Never = 0
Property is always serialized and deserialized, regardless of IgnoreNullValues configuration.
WhenReading = 5
WhenWriting = 4
Property is ignored only if it equals the default value for its type.
WhenWritingNull = 3
Property is ignored if its value is null. This is applied only to reference-type properties and fields.