public void setIterations(int iterations) throws Exception {
        if (iterations <= 0) {
            throw new Exception(
                    "Number of iterations is not greater than zero");
        }
        this.iterations = iterations;
    }
Sets the number of hills to grow. More hills usually mean a nicer
heightmap.

@param iterations
           the number of hills to grow
@throws Exception
            if iterations is not greater than zero
jme3-terrain/src/main/java/com/jme3/terrain/heightmap/HillHeightMap.java