code: public boolean collapsePanel() {
          if (mFirstLayout) {
              mSlideState = SlideState.COLLAPSED;
              return true;
          } else {
              if (mSlideState == SlideState.HIDDEN || mSlideState == SlideState.COLLAPSED)
                  return false;
              return collapsePanel(mSlideableView, 0);
          }
      }
docs: Collapse the sliding pane if it is currently slideable. If first layout
  has already completed this will animate.
  
  @return true if the pane was slideable and is now collapsed/in the process of collapsing