LayoutParams refreshMargins(LayoutParams lp) {
        if(rtl) {
            lp.setMargins(size, 0, 0, 0);
        } else {
            lp.setMargins(0, 0, size, 0);
        }
        return lp;
    }
Devs should not normally need to extend this class. Just use {@link CustomIndicator} instead.
However, this is public to leave the option open.

T is the interface needed in the corresponding {@link RecyclerView.Adapter}.
U is the sub-class of indicator.
The second parameter for the constructor is the class of T.
lib/src/main/java/com/turingtechnologies/materialscrollbar/Indicator.java