Original text:
and therefore distinct from the hostname transport address of the associated mDNS candidate, and as such MUST NOT be considered redundant per the guidance in RFC8445, Section 5.1.3.  To avoid <del> accidental IP address, this server-reflexive candidate MUST have its raddr field set to 0.0.0.0 and its rport field set to 0. </del>  Once an address has been identified as public, the ICE agent MAY cache this information and omit mDNS protection for that address in 3.1.2.3. The mDNS name of an mDNS candidate MUST be used in the connection- <del> address field of its candidate attribute.  When an mDNS candidate is the default candidate, its mDNS name MUST be used in the connection- address field of the SDP "c=" line.  Since an mDNS candidate also conceals its address family, the "c=" line SHOULD use "IP4" in the address-type field. </del>  Any candidates exposed to the application via local descriptions MUST be identical to those provided during candidate gathering (i.e., MUST

Reviewer comments:
ping
NAME , PTAL
LGTM too
Currently it contains: c=IN IP4 address/ttl Obviously, putting one of the candidate's IP address there would defeat the purpose of use mDNS. Options: Can this be omitted? Should it have a fake IP address of the right address family? Should it be allowed to have an mDNS name?
Just use the mDNS name.
If we run into issues, we could use 0.0.0.0:9 as we do when there are no candidates, but that starts to get complicated (i.e. may require updates to other specs)
mDNS name with IP4?
good point - shouldn't matter that much, but IP4 seems like the safest choice.
Agreed to use mDNS + IP4. We'll reevaluate if this causes problems.
Fixed by
We have observed an interop issue in the experimental deployment. Endpoints can fail to parse the SDP when the c= line contains a FQDN. This is the current solution.
Well, at least we thought of the solution already :)

Revised text:
and therefore distinct from the hostname transport address of the associated mDNS candidate, and as such MUST NOT be considered redundant per the guidance in RFC8445, Section 5.1.3.  To avoid  <ins> accidental IP address disclosure, this server-reflexive candidate MUST have its raddr field set to "0.0.0.0"/"::" and its rport field set to "9", as discussed in ICESDP, Section 9.1. </ins> Once an address has been identified as public, the ICE agent MAY cache this information and omit mDNS protection for that address in 3.1.2.3. The mDNS name of an mDNS candidate MUST be used in the connection-  <ins> address field of its candidate attribute.  However, when an mDNS candidate would be the default candidate, typically because there are no other candidates, its mDNS name MUST NOT be used in the connection-address field of the SDP "c=" line, as experimental deployment has indicated that many remote endpoints will fail to handle such a SDP.  In this situation, the IP address values "0.0.0.0"/"::" and port value "9" MUST instead be used in the c= and m= lines, similar to how the no-candidates case is handled in ICESDP, Section 4.3.1. </ins> Any candidates exposed to the application via local descriptions MUST be identical to those provided during candidate gathering (i.e., MUST