When we backdate an issue we use the newest date from all the locations in the issue set (primary and secondary). Similarly, issue assignment should go to the committer on the newest line.
The easiest example for this is "Method complexity should not be too high". Currently the last one to touch the method signature will be assigned a new issue from this rule, but in fact it should go to the last committer in the set of contributing lines. The same can be said of a new NPE issue - currently the issue would be assigned to the last one to touch the line where the NPE would actually be raised, but it more properly belongs to the last one to touch a line in the NPE flow.