When using PhysicsShape with PhysicsShapeDefinition.startMassUpdate disabled, for the purpose of setting the PhysicsBody.massConfiguration directly, the PhysicsBody is not configured correctly unless PhysicsBody.ApplyMassFromShapes is called.

This is by design by Box2D however it is not intuitive.

In additional, there are only getters that directly expose the mass, rotationalInertia and localCenterOfMass so a full MassConfiguration must be set. To make this more intuitive, we should add setters for these properties.

Finally, the scripting documentation is rather sparse in describing these methods and properties so they should be improved too.

Discussions Post: [https://discussions.unity.com/t/physicscore-2d-is-it-required-to-call-applymassfromshapes-before-setting-massconfiguration]