geopackage-sdk/src/main/java/mil/nga/geopackage/extension/style/FeatureStyleExtension.java
private long getOrInsertIcon(IconRow icon) {
        long iconId;
        if (icon.hasId()) {
            iconId = icon.getId();
        } else {
            IconDao iconDao = getIconDao();
            iconId = iconDao.create(icon);
        }
        return iconId;
    }
private long getOrInsertIcon(IconRow icon) {
        long iconId;
        if (icon.hasId()) {
            iconId = icon.getId();
        } else {
            IconDao iconDao = getIconDao();
            iconId = iconDao.create(icon);
        }
        return iconId;
    }
Get the icon id, either from the existing icon or by inserting a new one

@param icon icon row
@return icon id