@Override
    public SelectorDO findByNameAndNamespaceId(final String name, final String namespaceId) {
        List<SelectorDO> doList = selectorMapper.selectByNameAndNamespaceId(name, namespaceId);
        return CollectionUtils.isNotEmpty(doList) ? doList.get(0) : null;
    }
find selector by id and namespaceId.

@param id primary key.
@return {@link SelectorVO}
shenyu-admin/src/main/java/org/apache/shenyu/admin/service/impl/SelectorServiceImpl.java