bytes property
Bytes is how many bytes the file now holds. A write REPLACES the file, so this is its whole length and not an amount appended, and 0 is a legitimate answer: a WriteIn with no Data truncates the file to nothing.
Please note: This property should have been non-nullable! Since the specification file does not include a default value (using the "default:" property), however, the generated source code must fall back to having a nullable type. Consider adding a "default:" property in the specification file to hide this note.
Implementation
int? bytes;