@Override
    public void getRandomPoint(Vector3f store) {
        int meshIndex = FastMath.nextRandomInt(0, vertices.size() - 1);
        int vertIndex = FastMath.nextRandomInt(0, vertices.get(meshIndex).size() - 1);
        store.set(vertices.get(meshIndex).get(vertIndex));
    }
This method fills the point with coordinates of randomly selected mesh vertex.
@param store
       the variable to store with coordinates of randomly selected mesh vertex
jme3-core/src/main/java/com/jme3/effect/shapes/EmitterMeshVertexShape.java