Fix for b/12423037 - Exception while calling getDocContent

Changing Path.getFileName() to use Path.toFile() since Path.getFileName() fails
for UNC paths.
diff --git a/src/com/google/enterprise/adaptor/fs/FsAdaptor.java b/src/com/google/enterprise/adaptor/fs/FsAdaptor.java
index 66f3748..03e2d48 100644
--- a/src/com/google/enterprise/adaptor/fs/FsAdaptor.java
+++ b/src/com/google/enterprise/adaptor/fs/FsAdaptor.java
@@ -430,7 +430,8 @@
 
   @VisibleForTesting
   String getPathName(Path file) {
-    return file.getFileName().toString();
+    // NOTE: file.getFileName() fails for UNC paths. Use file.toFile() instead.
+    return file.toFile().getName();
   }
 
   private boolean isSupportedPath(Path p) throws IOException {