code: public void setPosition(String position)
      {
          if (position == null)
          {
              String message = Logging.getMessage("nullValue.PositionIsNull");
              Logging.logger().severe(message);
              throw new IllegalArgumentException(message);
          }
          this.position = position;
          clearControls();
      }
docs: Sets the relative viewport location to display the view controls. Can be one of {@link AVKey#NORTHEAST}, {@link
  AVKey#NORTHWEST}, {@link AVKey#SOUTHEAST}, or {@link AVKey#SOUTHWEST} (the default). These indicate the corner of
  the viewport to place view controls.
  
  @param position the desired view controls position, in screen coordinates.