Major Description
Relevant change
Version 2.15.0 of commons-io features performance improvements by ggregory for PathUtils.fileContextEquals() as listed in the changelog:
Improve performance of PathUtils.fileContentEquals(Path, Path, LinkOption[], OpenOption[]) by about 60%, see PathUtilsContentEqualsBenchmark.
The relevant change occurs in commit dd93554b, where the comparison of input streams through IOUtils.contentEquals() is replaced with RandomAccessFile.contentEquals().
Issue description
The issue occurs in RandomAccessFileMode.create(), where Path.toFile() is called. This method like many in Path, can throw an UnsupportedOperationException if it is not implemented by the filesystem provider.
In our particular case, we compare files from a zip archive with files on disk using the zip filesystem provider that was introduced in Java 7. The class jdk.nio.zipfs.ZipPath does not implement Path.toFile() and therefore throws an UnsupportedOperationException.
Though it does not seem unreasonable to limit the functionality of this method to a specific subset of Path implementations, this does seem to be a substantial breaking change in behavior of an existing method, which I am not sure was intentional.
As a workaround to resolve the issue without downgrading, we now call IOUtils.contentEquals() directly.