private static <T> T loadShims(Map<String, String> classMap, Class<T> xface) {
    String vers = getMajorVersion();
    String className = classMap.get(vers);
    return createShim(className, xface);
  }
Factory method to get an instance of HadoopShims based on the
version of Hadoop on the classpath.
shims/common/src/main/java/org/apache/hadoop/hive/shims/ShimLoader.java