@Override
    public void read(JmeImporter im) throws IOException {
        super.read(im);
        InputCapsule capsule = im.getCapsule(this);
        heightStickWidth = capsule.readInt("heightStickWidth", 0);
        heightStickLength = capsule.readInt("heightStickLength", 0);
        heightScale = capsule.readFloat("heightScale", 0);
        minHeight = capsule.readFloat("minHeight", 0);
        maxHeight = capsule.readFloat("maxHeight", 0);
        upAxis = capsule.readInt("upAxis", 1);
        heightfieldData = capsule.readFloatArray("heightfieldData", new float[0]);
        flipQuadEdges = capsule.readBoolean("flipQuadEdges", false);
        createShape();
    }
Uses Bullet Physics Heightfield terrain collision system. This is MUCH faster
than using a regular mesh.
There are a couple tricks though:
   -No rotation or translation is supported.
   -The collision bbox must be centered around 0,0,0 with the height above and below the y-axis being
   equal on either side. If not, the whole collision box is shifted vertically and things don't collide
   as they should.

@author Brent Owens
jme3-jbullet/src/main/java/com/jme3/bullet/collision/shapes/HeightfieldCollisionShape.java