add field constraint in lockfile.json

[monperrus]

constraint would contain the version ranges

[monperrus]

maybe constraint should be constraints (plural) and store an array

[MartinWitt]

We have now the original maven version constraint for every dependency. Maven calls this: VersionRange. Sadly this a bit verbose. See

"versionRange": {
        "recommendedVersion": {
          "majorVersion": 5,
          "minorVersion": 9,
          "incrementalVersion": 2,
          "comparable": {
            "value": "5.9.2",
            "items": [
              {
                "value": 5
              },
              {
                "value": 9
              },
              {
                "value": 2
              }
            ]
          }
        },
        "restrictions": []
      }

I would keep it in this format for now and later talk about usability improvements. In this current format we can use the maven version range tooling and don't have to write it ourselves.