1(2H)-isoquinolinone, 2-[3-[2-amino-6-[1,2,3,6-tetrahydro-1-(3-oxetanyl)-4-pyridinyl]-7H-pyrrolo[2,3-d]pyrimidin-4-yl]-2-(hydroxymethyl)phenyl]-6-cyclopropyl-8-fluoro-, methanesulfonate (1:2) (salt)