Function multipart_uploaded_file_parts 

fn multipart_uploaded_file_parts(
    content_type: &str,
    body: &[u8],
    field_name: &str,
    max_parts: usize,
    max_total_bytes: usize,
    allow_empty: bool,
) -> Vec<MultipartFilePart>

Applies filename validation and the caller’s empty-file policy to bounded multipart parts.