@Override
    public void read(JmeImporter im) throws IOException {
        super.read(im);
        InputCapsule ic = im.getCapsule(this);
        normalVelocity = ic.readFloat("normalVelocity", 0.0f);
        surfaceTangentFactor = ic.readFloat("surfaceTangentFactor", 0.0f);
        surfaceTangentRotation = ic.readFloat("surfaceTangentRotation", 0.0f);
    }
This method returns the surface tangent rotation factor.
@return the surface tangent rotation factor
jme3-core/src/main/java/com/jme3/effect/influencers/NewtonianParticleInfluencer.java