code: TextOutline positionMassLabel(TextOutline massLabel, TextOutline elementLabel) {
          final Rectangle2D elementBounds = elementLabel.getBounds();
          final Rectangle2D massBounds = massLabel.getBounds();
          return massLabel.translate((elementBounds.getMinX() - padding) - massBounds.getMaxX(),
                                     (elementBounds.getMinY() - (massBounds.getHeight() / 2)) - massBounds.getMinY());
      }
docs: Position the mass label relative to the element label. The mass adjunct is position to the
  top left of the element label.
  
  @param massLabel    mass label outline
  @param elementLabel element label outline
  @return positioned mass label