Establishing SSL connection without server‘s identity verification is not recommended.问题解决

Establishing SSL connection without server's identity verification is not recommended. 
According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set.
For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'.
You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification

这个错误原因是pom依赖中mysql的版本号不对，
去改下mysql依赖的版本号。