code: private <T> boolean isKeyEquals(T t1, T t2, List<Field> fields) {
  		if(t1 == null || t2 == null || fields == null) {
  			 return false;
  		}
  		List<Field> keyFields = DOInfoReader.getKeyColumns(t1.getClass());
  		if(keyFields == null || keyFields.isEmpty()) {
  			return false;
  		}
  		for(Field keyField : keyFields) {
  			Object key1 = DOInfoReader.getValue(keyField, t1);
  			Object key2 = DOInfoReader.getValue(keyField, t2);
  			if(key1 == null || key2 == null || !key1.equals(key2)) {
  				return false;
  			}
  		}
  		return true;
  	}
docs: 判断两个对象的key是否相等,只有都存在所有的key，且key（如多个，则每个）都相等，才返回true
  @param t1
  @param t2
  @param fields
  @return