Improve exception logging for Processors

Unfortunately while the title says "improve", I am logging it as a BUG for the following reasons.
A client reported an issue with one of the processors where the only visible message in both bulletin and logs is the message produced by ProcessLogger which does not seem to log a full stack trace. A typical pattern in current processor implementation is to have a significant code in onTrigger() method to be wrapped in try/catch where exception is logged and then re-thrown. Unfortunately it's not the case for this particular processor. As a result it is impossible to determine the cause of the root problem.
While immediate solution is to modify the specific Processor by wrapping its significant code in try/catch a better solution would be to improve ProcessLogger to log full stack trace whenever there is an error.