public static synchronized void addName(Class<?> writableClass, String name) {
    NAME_TO_CLASS.put(name, writableClass);
  }
@Test
  public void testAddName() throws Exception {
    Configuration conf = new Configuration();
    String altName = testName + ".alt";

    WritableName.setName(SimpleWritable.class, testName);
    WritableName.addName(SimpleWritable.class, altName);

    Class<?> test = WritableName.getClass(altName, conf);
    assertTrue(test.equals(SimpleWritable.class));

    // check original name still works
    test = WritableName.getClass(testName, conf);
    assertTrue(test.equals(SimpleWritable.class));
  }