The text says it's 'not good to go empty-handed' to a Guru. Can you explain this using the story of Kaka?

The principle of not approaching a Guru empty-handed is a traditional sign of respect and humility, and this is perfectly illustrated in Chapter 35. This chapter mentions the belief that one should not go 'empty-handed to the door of God, a priest, or a Guru.' Following this custom, a devotee named Kaka bought two seers of grapes as an offering before going for Sai Baba's darshan. This simple act of devotion, though the grapes were the common variety with seeds, became the very tool Baba used to perform a miracle for Boss Dharamsee. It shows how a sincere offering, no matter how simple, can be used by the Guru for a greater spiritual purpose.