public void setDefaultIndicatorShape(Shape shape){
        if(mUserSetSelectedIndicatorResId == 0){
            if(shape == Shape.Oval){
                mSelectedGradientDrawable.setShape(GradientDrawable.OVAL);
            }else{
                mSelectedGradientDrawable.setShape(GradientDrawable.RECTANGLE);
            }
        }
        if(mUserSetUnSelectedIndicatorResId == 0){
            if(shape == Shape.Oval){
                mUnSelectedGradientDrawable.setShape(GradientDrawable.OVAL);
            }else{
                mUnSelectedGradientDrawable.setShape(GradientDrawable.RECTANGLE);
            }
        }
        resetDrawable();
    }
if you are using the default indicator, this method will help you to set the shape of
indicator, there are two kind of shapes you  can set, oval and rect.
@param shape
library/src/main/java/com/daimajia/slider/library/Indicators/PagerIndicator.java