I have the following Jenkins versions and plugins:

Jenkins 2.426.3

database:247.v244b_d85f086d
database-mysql:63.va_0596d2b_1438

And here is my code to connect to mysql db:

Class.forName("com.mysql.cj.jdbc.Driver")

def url = 'jdbc:mysql://<host>:<port>/<db>'
def driver = 'com.mysql.cj.jdbc.Driver'
def sql = Sql.newInstance(url, "${username}", "${password}", driver)

It fails with No suitable driver found.

From all the questions/answers I was reading on stackoverflow I think the reason to the failure is that mysql-connector-java driver is not in the CLASSPATH.

One of the answers suggested finding classpath from Jenkins Script Console and here is what I found:

System.getProperty("java.class.path")
Result: /usr/lib/jenkins/jenkins.war

How can I find where mysql-connector-java driver is located?
And how to add it to CLASSPATH?