I think Pretorian noticed this a few weeks back, but I just noticed it again now.
Section 3.1 of the ADC Protocol states that client addresses should be in “RFC 1884 form for IPv6.” This document has been obsoleted by several others, the latest being RFC4291. Additionally, RFC5952 provides updated recommendations for the textual representation of IPv6 addresses.
For combining an IPv6 address with a port number, RFC5952 recommends using the square bracket notation from RFC3986 (the URI syntax), e.g. adc://[2001:db8::1]:4110/, where 2001:db8::1 is the IPv6 address, and the port number is 4110.