Why does 'Time spent can not be set to zero' message appear on the resolve screen?

[Sergey Shmarkatyuk]

I have noticed strange JIRA 5.1.2 behaviour. If I leave field 'time spent' empty on the resolution screen, JIRA does not show any validation messages and successfully resolves issue without logged work records. But when I put '0h' into , it says 'Time spent can not be set to zero' when I press 'Resolve' button even though leaving 'time spent' field empty is semantically equal to putting '0h' value there. Notice that there are no custom workflow validators for the 'Resolve' transition configured.

Is that an expected JIRA behaviour or is this a bug?

[dleng · Accepted solution]

If the Time Spent field is NOT required in the field configuration and you leave it blank, then JIRA simply thinks that you did not spend any time on the issue. Consequently if you DID put in a value into the field, then JIRA is obviously looking for any value more than a minute, since the only reason why you would want to key in a value is because you DID spent time on the issue. Expected behaviour, I'd say?

[Sergey Shmarkatyuk]

ok, no problem with that. just wanted some third-party opinion to explain jira users I work with "why is it so". thanks!