Refinement of Newton Gravitation Law

According to the theory of general relativity and experiments with atomic clocks in gravitation field, presence of the field shall cause time dilation of clock at rest in the field. This means that the gravitation constant G is not a true physical constant, but rather a function of the location of the setup in the field when measuring the parameter. This is because the definition of G includes a unit of time, and duration of that time unit is influenced by clock’s location in the field. However, the theory assumes a prior that G shall remain constant in gravitation field, even though this may not be the case. On the other hand, relativistic gravitation phenomena can be derived without contradiction from a refined version of Newton’s law of gravitation that complies with Einstein’s law of mass-energy equivalence.