This needs to be done when you create the Box2DLight's Light object instead of inside the Box2D code you posted.

You can fix this by setting the setSoftnessLength(float) on the Light object.

For example:

m_Light = new PointLight(...);
m_Light.setSoftnessLength(1.5f);

This needs to be done when you create the Box2DLight's Light object.

You can fix this by setting the setSoftnessLength(float) on the Light object.

For example:

m_Light = new ConeLight(...);
m_Light.setSoftnessLength(1.5f);