Device does not send DHCP Decline message when an address conflict is detected

RFC 2131 states:
"If the client detects that the address is already in use (e.g., through the use of ARP), the client MUST send a DHCPDECLINE message to the server and restarts the configuration process." [RFC2131]

In case the lwIP stack is used together with EtherNet/IP, the ACD protocol (which checks for duplicate IP addresses) must take care to trigger a DHCP decline message on the network and restart configuration.