encodeNotNullMark

Notifies the encoder that value of a nullable type that is being serialized is not null. It should be called before writing a non-null value of nullable type:

// Could be String? serialize method
if (value != null) {
    encoder.encodeNotNullMark()
    encoder.encodeStringValue(value)
} else {
    encoder.encodeNull()
}

This method has a use in highly-performant binary formats and can be safely ignore by most of the regular formats.