[MNG-7594] ComparableVersion#getCanonical() returns incorrect results for zero between hyphens

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.8.6
• Component/s: Core
• Assignee: Unassigned
• Reporter: Niklas Matthies
• Created: 08/Nov/22 16:23
• Updated: 24/Dec/22 21:43

Description

The getCanonical() method incorrectly reduces version strings like "1-0-1" to "1-1". This leads to contradictory results like in:

$ java -jar /path/to/maven-artifact-3.8.x.jar 1-0-1 1-1
1. 1-0-1 -> 1-1; tokens: [1, [[1]]]
   1-0-1 < 1-1
2. 1-1 -> 1-1; tokens: [1, [1]]

Here 1. and 2. imply that both versions should be equal, but they still compare unequal (1-0-1 < 1-1). Arguably, the correct canonicalization for 1-0-1 here should be 1--1 (two hyphens), since 1--1 compares equal to 1-0-1.

This is related to Bug 2 of MNG-6420, but could probably be fixed separately. I.e. just fix the broken canonicalization to make it consistent with compareTo(), but keep the comparison unchanged, without having to wait for a new spec to be written.

Note: This assumes that compareTo() is well-behaved for equality, i.e. defines a sound equivalence relation, which I think it does. It doesn't define a correct total order, as issues like MNG-6568 demonstrate, but that isn't relevant for making getCanonical() consistent with compareTo().