Can you tell me the full story of Cholkar and his vow to Sai Baba?

The story of Cholkar is a beautiful account of faith and devotion. As detailed in Chapter 15, Cholkar was a man from a poor household who needed to pass an examination to secure his job. He made a vow to Sai Baba that if he passed, he would visit Shirdi and distribute sugar candy. His wish was granted, but due to financial difficulties, he was delayed in fulfilling his promise. As a personal penance during this delay, Cholkar gave up eating sugar entirely. When he finally reached Shirdi and fulfilled his vow, Baba demonstrated his omniscience by specifically telling another devotee, Jog, to serve Cholkar tea "well-filled with sugar," revealing that He knew about Cholkar's secret sacrifice all along. This incident deeply strengthened Cholkar's faith.