presto-base-jdbc/src/main/java/io/prestosql/plugin/jdbc/credential/CredentialConfig.java/CredentialConfig/setConnectionUser
class CredentialConfig:    @Config("connection-user")
    @ConfigDescription("user name for JDBC client")
    public CredentialConfig setConnectionUser(String connectionUser)
    {
        this.connectionUser = connectionUser;
        return this;
    }