where is pop3_migration_ignore_missing_uidls=yes set?

[Leon Kyneur]

While doing pop3 migrations with dsync I am getting an error:

dsync(user at domain.net): Error: pop3_migration: 2 POP3 messages have no 
matching IMAP messages (first POP3 msg 2638 UIDL 
fb3d6f3299541e695a28585f5803ed1c) - set 
pop3_migration_ignore_missing_uidls=yes to continue anyway
dsync(user at domain.net): Error: Exporting mailbox INBOX failed: Can't 
lookup pop3-uidl for UID=3252: POP3 UIDLs couldn't be synced

Can't see this is doveconf -a so it's not a setting? - tried configuring 
it as a plugin setting but that didn't work...

Where is the correct place to set this?

TIA