Ignore property when null using the new Net Core 3.0 Json

I’m looking at .Net Core 3.1, where this should ignore null values

services.AddControllers().AddJsonOptions(options =>
{
    options.JsonSerializerOptions.IgnoreNullValues = true;
});

While in .NET 5 and later, set JsonSerializerOptions.DefaultIgnoreCondition to JsonIgnoreCondition.WhenWritingNull:

services.AddControllers().AddJsonOptions(options =>
{
    options.JsonSerializerOptions.DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull;
});

Note, the above isn’t per property/attribute, although there is an attribute which may be helpful JsonIgnoreAttribute.

An alternative, to solve your problem might be a JsonConverterAttribute, information on how to write your own converter is here