The context data specifies multiple files with their attributes. The expression filters based on conditions such as file size greater than 6000 and file type equals text/html. Based on the file size and file type criteria, the correct file is the first one listed in the context data. The SHA1 hash for this file is 'e6ef5142e2553c1e442a0ffac07636eac61e6edd'. The expression includes a transformer to change the case to upper, thus the expected output is 'E6EF5142E2553C1E442A0FFAC07636EAC61E6EDD'.