code: public String determineDriverClassName() {
  		if (StringUtils.hasText(this.driverClassName)) {
  			Assert.state(driverClassIsLoadable(),
  					() -> "Cannot load driver class: " + this.driverClassName);
  			return this.driverClassName;
  		}
  		String driverClassName = null;
  		if (StringUtils.hasText(this.url)) {
  			driverClassName = DatabaseDriver.fromJdbcUrl(this.url).getDriverClassName();
  		}
  		if (!StringUtils.hasText(driverClassName)) {
  			driverClassName = this.embeddedDatabaseConnection.getDriverClassName();
  		}
  		if (!StringUtils.hasText(driverClassName)) {
  			throw new DataSourceBeanCreationException(
  					"Failed to determine a suitable driver class", this,
  					this.embeddedDatabaseConnection);
  		}
  		return driverClassName;
  	}
docs: Determine the driver to use based on this configuration and the environment.
  @return the driver to use
  @since 1.4.0