(1) fixed a test case that failed to reset the access path lengtrh
(2) duplicated a test case with a shorter access path length and fixed the code to correctly handle this case
(3) added a test case with two secret integers being added and the result being leaked and fixed the path construction algorithm for the test case to work
cleaned up the code and added an assertion
(1) extended the taint propagation handlers to be called for all kinds of data flow edges
(2) added some JavaDoc comments for the taint propagation handlers