The key value

javac.opt.Xlint.desc.synchronization=\
    Warn about synchronization attempts on instances of value-based classes.\n\
\ This key is a deprecated alias for ''identity'', which has the same uses and\n\
\ effects. Users are encouraged to use the ''identity'' category for all future\n\
\ and existing uses of ''synchronization''.

Contains ''identity'' and ''synchronization'' which should not be translated. Providing a comment to make this apparent would be helpful for IPS translators and also consistent with other key values in the resource file that make similar l10n related comments.