CommandContext.buildRequest(line) throws OperationFormatException for wrong reason

Operation requests aren't affected.
The method translates commands to operation requests. Of course, the command handler is required to implement OperationCommand interface. But the if condition is wrong, i.e. instead of throwing an exception in case the handler doesn't implement the interface, it throws an exception if the handler does implement the interface.

This is a new and not yet publicly advertised functionality, so nobody will suffer from this bug.