public boolean isResend() {
        return resend;
    }
Identifies whether an exception was thrown during a resend of a
message or not.  In this case a resend refers to whether the
message is being resent from the buffer of messages internal.
This would occur if we sent 5 messages quickly to APNS:
1,2,3,4,5 and the 3 message was rejected.  We would
then need to resend 4 and 5.  If a network exception was
triggered when doing this, then the resend flag will be
{@code true}.
@return {@code true} for an exception trigger during a resend, otherwise {@code false}.
src/main/java/com/notnoop/exceptions/NetworkIOException.java