You are correct of course - though the two phenomena are inextricably linked (mass/gravity) - so much is still unknown.

I should have stated more clearly that this is the way we calculate gravity at present and this is correct to a very fine amount. From my Layman's point of view. - there are more relativistic points to be looked at to precise - including spin as any motion creates energy and it is the total energy that dictates the mass in a ystem and hence the gravity. If the spin is increasing it is acceleration and adds to the gravity - I'm not sure about constant rates of spin though.

Anyone?