private String getCollName(String collName) {
        if (StringUtils.isNotEmpty(collName)) {
            return collName;
        }
        if (StringUtils.isNotEmpty(getDefaultCollName())) {
            return getDefaultCollName();
        }
        throw new IllegalArgumentException("collName can not be null!");
    }
@author Robert HG (254963746@qq.com) on 5/28/15.
lts-core/src/main/java/com/github/ltsopensource/store/mongo/MongoTemplate.java