private <Type> Class<? extends Type> forName(String className, Class<Type> type) {
      Class<? extends Type> clazz;
      try {
        clazz = Class.forName(className).asSubclass(type);
      } catch (ClassNotFoundException e) {
        throw new IllegalStateException("Could not find class for name: " + className, e);
      }
      return clazz;
    }
configuration parameter name that contains the PE impl
hbase-rest/src/test/java/org/apache/hadoop/hbase/rest/PerformanceEvaluation.java