src/main/java/j2html/tags/Tag.java
boolean setAttribute(String name, String value) {
        if (value == null) {
            return attributes.add(new Attribute(name));
        }
        for (Attribute attribute : attributes) {
            if (attribute.getName().equals(name)) {
                attribute.setValue(value); // update with new value
                return true;
            }
        }
        return attributes.add(new Attribute(name, value));
    }
boolean setAttribute(String name, String value) {
        if (value == null) {
            return attributes.add(new Attribute(name));
        }
        for (Attribute attribute : attributes) {
            if (attribute.getName().equals(name)) {
                attribute.setValue(value); // update with new value
                return true;
            }
        }
        return attributes.add(new Attribute(name, value));
    }
Sets an attribute on an element

@param name  the attribute
@param value the attribute value