@Override
    public void render(Context context, Column column, SafeHtmlBuilder sb) {
        // Get the view data.
        Object key = context.getKey();
        ViewData viewData = getViewData(key);
        final String value = getValue(column);
        if (viewData != null && viewData.getCurrentValue().equals(value)) {
            clearViewData(key);
            viewData = null;
        }

        String s = (viewData != null)
                ? viewData.getCurrentValue()
                : value;
        if (s != null) {
            sb.append(template.input(s));
        } else {
            sb.append(template.input(""));
        }
    }
Constructs a TextInputCell that renders its text without HTML markup.
stroom-core-client/src/main/java/stroom/dashboard/client/table/FilterCell.java