public final int getPeekHeight() {
        return mPeekHeightAuto ? PEEK_HEIGHT_AUTO : mPeekHeight;
    }
Gets the height of the bottom sheet when it is collapsed.

@return The height of the collapsed bottom sheet in pixels, or {@link #PEEK_HEIGHT_AUTO}
        if the sheet is configured to peek automatically at 16:9 ratio keyline
@attr ref android.support.design.R.styleable#BottomSheetBehavior_Layout_behavior_peekHeight
vpbs/src/main/java/biz/laenger/android/vpbs/ViewPagerBottomSheetBehavior.java