get Literal Log Message
Returns the single literal value as a string. This method must never be called if the log data has arguments to be formatted.
This method is designed to be paired with mustBeFormatted and can always be safely called if that method returned false for the same log data.
Return
the single logged value as a string.
Parameters
log Data
the log statement data.
Throws
if the log data had arguments to be formatted (i.e. there was a template context).