Case T-285/19: Judgment of the General Court of 14 April 2021 — SGI Studio Galli Ingegneria v Commission (Arbitration clause — Seventh Framework Programme for research, technological development and demonstration activities (2007-2013) — Grant agreement — The MARSOL Project — Eligible costs — OLAF investigation report finding certain expenses incurred to be ineligible — Repayment of sums paid — Burden of proof — Principle of good faith — Right to be heard — Principle of sound administration — Rights of the defence — Proportionality)