We got the following feedback on the Migrating databases to MariaDB instances chapter in the 18.0 adoption guide:

• Section 3.5, step 2:
  The shell script uses a for loop, which they complete with an "end" statement, but it should be "done"
• Section 3.5, step 3:
  The shell script has this:

 $ test -z "$PULL_OPENSTACK_CONFIGURATION_MYSQLCHECK_NOK"  || [ "x$PULL_OPENSTACK_CONFIGURATION_MYSQLCHECK_NOK" = "x " ] && echo "OK" || echo "CHECK FAILED"

However, the shell variable is an array, so the test -z check doesn't work, failing with:
 "PULL_OPENSTACK_CONFIGURATION_MYSQLCHECK_NOK: unbound variable"
 It seems like this should be moved into the for loop and checked with the array variable.