if (files == null) {
boolean exists = f.exists();
boolean isDirectory = f.isDirectory();
boolean canRead = f.canRead();
boolean canWrite = f.canWrite();
throw new CacheLoaderException(String.format(
"File %s is not directory or IO error occurred when listing " +
"files with filter %s [fileExists=%b, isDirector=%b, " +
"canRead=%b, canWrite=%b]",
f, filter, exists, isDirectory, canRead, canWrite));
}