Github user reudismam commented on the issue:
https://github.com/apache/giraph/pull/81
Strings can be used to represent a file system path even though some
classes are specifically designed for this task. For instance, java.nio.Path.
It is useful to change the type of the variable to Path, since strings can be
combined in an undisciplined way, which can lead to invalid paths. Second,
different operating systems use different file separators, which can cause bugs---
