(\nabla (u-g)\cdot \nu _{x_0})_{\omega _r}|\nonumber \\&\quad \le c\left( \int _{\omega _r} \left|\nabla u - \nabla g - (\nabla (u-g) \cdot \nu _{x_0})_{\omega _r} \otimes \nu _{x_0}\right|^2 \,\textrm{d}x\right) ^{\frac{1}{2}} + cmr^{\...