void setSizeCustom(int size) {
        if(addSpace) {
           this.size =  size + Utils.getDP(10, this);
        } else {
            this.size =  size;
        }
        setLayoutParams(refreshMargins((LayoutParams) getLayoutParams()));
    }
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