Fix issue where stop points are sometimes added twice to index

[habrahamsson-skanetrafiken]

Summary

When netex data contains duplicate JourneyPatterns the scheduledStopPointsIndex will get duplicates of all the stop points for those JourneyPatterns during graph build. When the graph is loaded this will result in strange IndexOutOfBoundsExceptions in the TransferMapper.

Issue

NetexMapper uses a Multimap for the scheduledStopPointsIndex. But the semantics of a multimap is that putting to a key that already exists will extend any existing data that has already been added. This is not really the behaviour we want in this case.

This PR fixes this issue by replacing the Multimap with a Map<List>. This way we will replace the current values when calling putAll().

I suppose that duplicate JourneyPatterns could cause all kinds of other problems, so to solve the underlying issue we should really add some validation of the netex data for this. But I think these changes are worthwhile anyway, since it makes the code less brittle.

Unit tests

There aren't any tests for this code that I could find, and writing them feels a bit out of scope for this PR.

Documentation

Nothing needed.

Bumping the serialization version id

Nope

[codecov]

Codecov Report

Attention: 12 lines in your changes are missing coverage. Please review.

Comparison is base (a4eb912) 67.19% compared to head (a66b534) 67.18%.
Report is 1 commits behind head on dev-2.x.

Files	Patch %	Lines
.../opentripplanner/netex/mapping/TransferMapper.java	0.00%	12 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             dev-2.x    #5552      +/-   ##
=============================================
- Coverage      67.19%   67.18%   -0.01%     
- Complexity     16040    16041       +1     
=============================================
  Files           1850     1850              
  Lines          70921    70922       +1     
  Branches        7410     7409       -1     
=============================================
- Hits           47653    47652       -1     
- Misses         20801    20802       +1     
- Partials        2467     2468       +1     

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[t2gran]

When a duplicate is encountered it should result in an issue being added to the issue report. It might/might not be the case here, can you test if that is the case @jtorin ? If not we should add that, you may merge this PR and add another on or just append a commit this this - it is up to you.

[habrahamsson-skanetrafiken]

@t2gran That's a good point. I'll merge this and add that in a separate PR.