src/main/java/com/github/andrezimmermann/dropzone/client/injector/AbstractInjector.java
protected static HeadElement getHead() {
        if (head == null) {
            final Element element = Document.get().getElementsByTagName("head").getItem(0);
            assert element != null : "HTML Head element required";
            final HeadElement head = HeadElement.as(element);
            AbstractInjector.head = head;
        }
        return AbstractInjector.head;
    }
protected static HeadElement getHead() {
        if (head == null) {
            final Element element = Document.get().getElementsByTagName("head").getItem(0);
            assert element != null : "HTML Head element required";
            final HeadElement head = HeadElement.as(element);
            AbstractInjector.head = head;
        }
        return AbstractInjector.head;
    }
Gets the document header.

@return the document header