code: @Test public void testSubDelete(){
    Mutator<String> m=createMutator(keyspace,se);
    List<HColumn<String,String>> columnList=new ArrayList<HColumn<String,String>>();
    columnList.add(createColumn("col_1","val_1",se,se));
    columnList.add(createColumn("col_2","val_2",se,se));
    columnList.add(createColumn("col_3","val_3",se,se));
    HSuperColumn<String,String,String> superColumn=createSuperColumn("super_name",columnList,se,se,se);
    MutationResult r=m.insert("sk1","Super1",superColumn);
    SuperColumnQuery<String,String,String,String> scq=HFactory.createSuperColumnQuery(keyspace,se,se,se,se);
    scq.setColumnFamily("Super1");
    scq.setKey("sk1");
    scq.setSuperName("super_name");
    assertEquals(3,scq.execute().get().getColumns().size());
    m.discardPendingMutations();
    columnList.remove(1);
    columnList.remove(0);
    superColumn.setSubcolumns(columnList);
    m.addSubDelete("sk1","Super1",superColumn);
    m.execute();
    assertEquals(2,scq.execute().get().getColumns().size());
  }
  