/**
  * Returns one of AcaciaStairs sub-type based on facing direction and upside-down state. It will
  * never return null.
  *
  * @param blockFace facing direction of stairs.
  * @param upsideDown if stairs should be upside-down.
  * @return sub-type of AcaciaStairs
  */
 public static AcaciaStairsMat getAcaciaStairs(
     final BlockFace blockFace, final boolean upsideDown) {
   return getByID(StairsMat.combine(blockFace, upsideDown));
 }
 @Override
 public AcaciaStairsMat getUpsideDown(final boolean upsideDown) {
   return getByID(StairsMat.combine(this.face, upsideDown));
 }
 @Override
 public AcaciaStairsMat getType(final BlockFace face, final boolean upsideDown) {
   return getByID(StairsMat.combine(face, upsideDown));
 }
 @Override
 public AcaciaStairsMat getBlockFacing(final BlockFace face) {
   return getByID(StairsMat.combine(face, this.upsideDown));
 }