private static String getJar(Class<?> my_class) {
    String ret = null;
    try {
      ret = JarFinder.getJar(my_class);
    } catch (Exception e) {
      // toss all other exceptions, related to reflection failure
      throw new RuntimeException("getJar invocation failed.", e);
    }

    return ret;
  }
Invoke 'getJar' on a custom JarFinder implementation. Useful for some job configuration
contexts (HBASE-8140) and also for testing on MRv2. check if we have HADOOP-9426.
@param my_class the class to find.
@return a jar file that contains the class, or null.
hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapreduce/TableMapReduceUtil.java