import org.w3c.dom.html.HTMLInputElement; //导入依赖的package包/类
@Override
public Optional<String> getValue() {
    String value = null;
    if (element instanceof HTMLInputElement) {
        value = ((HTMLInputElement) element).getValue();
    } else if (element instanceof HTMLOptionElement) {
        value = ((HTMLOptionElement) element).getValue();
    }
    return value == null || value.isEmpty() ? Optional.empty() : Optional.of(value);
}
 

import org.w3c.dom.html.HTMLInputElement; //导入依赖的package包/类
private Element showHideCheckbox(String label, String className, boolean initiallyHidden) {
	Element LI = document.createElement("LI");
	HTMLInputElement checkbox = (HTMLInputElement) document.createElement("input");
	LI.appendChild(checkbox);
	LI.appendChild(document.createTextNode(label));
	checkbox.setAttribute("type", "checkbox");
	String arglist = "('" + className + "')";
	String show = "show_nodes_of_class" + arglist;
	String hide = "hide_nodes_of_class" + arglist;
	checkbox.setAttribute("onchange", "if (this.checked) {" + hide + "} else {" + show + "}");
	checkbox.setChecked(initiallyHidden);
	return LI;
}
 

import org.w3c.dom.html.HTMLInputElement; //导入依赖的package包/类
@Override
public Element setValue(String value) {
    if (element instanceof HTMLInputElement) {
        ((HTMLInputElement) element).setValue(value);
    } else if (element instanceof HTMLOptionElement) {
        ((HTMLOptionElement) element).setValue(value);
    }
    return this;
}
 

import org.w3c.dom.html.HTMLInputElement; //导入依赖的package包/类
public UserCredentials(HTMLInputElement username, HTMLInputElement password){
	this.username = username;
	this.password = password;
}