Modeling Exclusive API Parameters in Schema

export class SendSignature extends S.Class<SendSignature>('SendSignature')({
    title: String255,
    subject: String255,
    message: S.NonEmpty.pipe(S.maxLength(5000)),
    signers: S.nonEmptyArray(Signer),
    cc_email_addresses: S.optional(S.nonEmptyArray(EmailSchema)),
    // file_urls: S.nonEmptyArray(S.NonEmpty),
    // files: S.nonEmptyArray(S.NonEmpty),
    metadata: S.optional(S.record(S.NonEmpty, S.unknown)), //max 10 key value pairs
    signing_options: SigningOptions,
    field_options: S.struct({
        date_format: S.NonEmpty,
    }),
    test_mode: S.boolean,
}) {}