I have been reporting this error before, but I haven’t found out the reason. After looking at the code given by a senior, I found that the following two jar packages are missing, and then I won’t report any more errors.

        <dependency>
            <groupId>io.swagger</groupId>
            <artifactId>swagger-annotations</artifactId>
            <version>1.5.21</version>
        </dependency>
        <dependency>
            <groupId>io.swagger</groupId>
            <artifactId>swagger-models</artifactId>
            <version>1.5.21</version>
        </dependency>

After joining, click in again and you won’t report an error again.