Read the content of a watchlist value file. Note that the EsmFileData object will contain information on how many bytes were read, as well as the total size of the file. The size of the data returned may be less than count, depending on the amount of file data available. Note that the watchlist file property on EsmWatchlistDetails is used as a parameter to this call. The file will contain the values as they existed when the call to sysGetWatchlistDetails was made. If subsequent changes were made to the watchlist after getting the details, another EsmWatchlistDetails object should be obtained by calling sysGetWatchlistDetails before using its EsmWatchlistFile object to retrieve the updated list of watchlist values. This call is not supported for hidden watchlists, for example GTI.