what is the purpose creating new hashtable in quit function

can someone explain me what is the purpose of creating new hashtable object under quit function.
This is from july weekday batch framework.

public void quit() {
// close all browsers

if(table.get("Mozilla") != null){
table.get("Mozilla").quit();
}

if(table.get("Chrome") != null){
table.get("Chrome").quit();
}

table =new Hashtable<String,WebDriver>();

}