int rx_bytes = 1000;
int tx_bytes = 1000;
@Override
public DomainInterfaceStats answer(InvocationOnMock invocation) throws Throwable {
DomainInterfaceStats domainInterfaceStats = new DomainInterfaceStats();
domainInterfaceStats.rx_bytes = (this.rx_bytes += increment);
domainInterfaceStats.tx_bytes = (this.tx_bytes += increment);
return domainInterfaceStats;
}