docs: public float getChildSize(final int dataIndex, final Axis axis) {
          float size = 0;
          Widget child = mContainer.get(dataIndex);
          if (child != null) {
              switch (axis) {
                  case X:
                      size = child.getLayoutWidth();
                      break;
                  case Y:
                      size = child.getLayoutHeight();
                      break;
                  case Z:
                      size = child.getLayoutDepth();
                      break;
                  default:
                      throw new RuntimeAssertion("Bad axis specified: %s", axis);
              }
          }
          return size;
      }