code: public void fill(View view) {
          validateNotNullableView(view);
  
          try {
              if(view instanceof ViewGroup) {
                  ViewGroup viewGroup = (ViewGroup) view;
                  for(int i = 0; i < viewGroup.getChildCount(); i++) {
                      View child = viewGroup.getChildAt(i);
                      fill(child);
                  }
              } else {
                  if(mIds == null) {
                      fillView(view);
                  } else if(mIds.contains(view.getId())) {
                      fillView(view);
                  }
              }
          } catch (Exception e) {
              e.printStackTrace();
          } finally {
              mFaker = null;
          }
      }
docs: Fill a view with random data
  @param view target view