How did Sai Baba demonstrate that he knew what Boss Dharamsee was thinking about the grapes?

Chapter 35 clearly demonstrates Sai Baba's omniscience through his interaction with Boss Dharamsee. Dharamsee, who disliked grapes with seeds, had a thought arise in his mind: 'If he is a saint, how does he not know That I do not like these grapes? Why does he force them upon me?' The text explicitly states that as soon as this attitude arose in him, Baba gave him even more grapes, directly responding to his unvoiced challenge. Later, when the grapes miraculously became seedless, Dharamsee realized Baba had known his thoughts all along, thinking, 'Knowing the intent of my mind... Whatever Sai gives me, they turn out to be seedless and beneficial.' This proved Baba's ability to perceive his innermost thoughts.