public override string Serialize()
{
var builder = new JSONBuilder();
builder.WriteKeyValuePair(FEE_FIELD_KEY, Fee);
builder.WriteKeyValuePair(FEE_PAYING_ACCOUNT_FIELD_KEY, FeePayingAccount);
builder.WriteKeyValuePair(EXPIRATION_TIME_FIELD_KEY, DateTimeConverter.ConvertTo(ExpirationTime));
builder.WriteKeyValuePair(PROPOSED_OPS_FIELD_KEY, ProposedOperations);
builder.WriteOptionalStructKeyValuePair(REVIEW_PERIOD_SECONDS_FIELD_KEY, ReviewPeriodSeconds);
builder.WriteKeyValuePair(EXTENSIONS_FIELD_KEY, Extensions);
return(builder.Build());
}