My question involves labor and employment law for the state of: California

I am currently a student in a health related field. I will be going to a clinical at a Hospital which belongs to a government agency. A clinical is not employment or a volunteer position. I have a misdemeanor conviction that was expunged under Penal Code 1203.4 many year ago. On a request to perform a background check I was asked about criminal convictions. There was no statement saying that I must disclose all convictions even those expunged under 1203.4 as I have seen on employment and some volunteer applications. What is my obligation to disclose in this instance?