@Override
    public boolean accept(File file) {
      return file.isDirectory() || (file.getName().endsWith(CLASS_EXT) && (null == nameFilter
        || nameFilter.isCandidateFile(file.getName(), file.getAbsolutePath())));
    }
Finds the classes in a package and nested packages.
@param packageName         package names
@param proceedOnExceptions whether to ignore exceptions encountered for individual
                           jars/files/classes, and proceed looking for others.
hbase-common/src/test/java/org/apache/hadoop/hbase/ClassFinder.java