code: public int getChildCount(boolean includeHidden) {
          int count = 0;
          for (Widget child : getChildren()) {
              if (includeHidden || child.mVisibility == Visibility.VISIBLE) {
                  ++count;
                  count += child.getChildCount(includeHidden);
              }
          }
          return count;
      }
docs: Get a recursive count of the number of {@link Widget} children of this
  {@code Widget}.
  
  @param includeHidden
  Pass {@code false} to only count children whose
  {@link #setVisibility(Visibility) visibility} is
  {@link Visibility#VISIBLE}.
  @return The count of child {@code Widgets}.