[IO-872] PathUtils.directoryAndFileContentEquals doesn't work across

FileSystems

- Fix test
- Internal reuse

Author: garydgregory

src/main/java/org/apache/commons/io/file/PathUtils.java

@@ -1736,10 +1736,10 @@ public static BigInteger sizeOfDirectoryAsBigInteger(final Path directory) throw
         return countDirectoryAsBigInteger(directory).getByteCounter().getBigInteger();
     }
 
-    private static Path stripTrailingSeparator(final Path cdir) {
-        final Path dir = cdir.normalize();
+    private static Path stripTrailingSeparator(final Path path) {
+        final Path dir = path.normalize();
         final String separator = dir.getFileSystem().getSeparator();
-        final String fileName = Objects.toString(dir.getFileName(), null);
+        final String fileName = getFileNameString(dir);
         return fileName != null && fileName.endsWith(separator) ? dir.resolveSibling(fileName.substring(0, fileName.length() - 1)) : dir;
     }
 

src/test/java/org/apache/commons/io/file/PathUtilsContentEqualsTest.java

@@ -163,8 +163,8 @@ public void testDirectoryAndFileContentEqualsDifferentFileSystemsZipVsZipEmpty()
         Files.copy(emptyZip, zipCopy, StandardCopyOption.REPLACE_EXISTING);
         try (FileSystem fileSystem1 = FileSystems.newFileSystem(emptyZip, null);
                 FileSystem fileSystem2 = FileSystems.newFileSystem(zipCopy, null)) {
-            final Path dir1 = fileSystem1.getPath("");
-            final Path dir2 = fileSystem2.getPath("");
+            final Path dir1 = fileSystem1.getPath("/");
+            final Path dir2 = fileSystem2.getPath("/");
             // WindowsPath, UnixPath, and ZipPath equals() methods always return false if the argument is not of the same instance as itself.
             assertTrue(PathUtils.directoryAndFileContentEquals(dir1, dir2));
         }