code: public BottomNavigationItem setInactiveIcon(Drawable mInactiveIcon) {
          if (mInactiveIcon != null) {
              this.mInactiveIcon = mInactiveIcon;
              inActiveIconAvailable = true;
          }
          return this;
      }
docs: By default library will switch the color of icon provided (in between active and in-active icons)
  This method is used, if people need to set different icons for active and in-active modes.
  
  @param mInactiveIcon in-active drawable icon
  @return this, to allow builder pattern