versions:update-parent ignores allowSnapshots CLI parameter

[rillner]

Until release 2.11.0, it was possible to upgrade the current parent version (in this example 1.58.5-SNAPSHOT) to a fixed SNAPSHOT version which is not necessarily the latest SNAPSHOT (in this example 1.58.6-SNAPSHOT) via:

mvn -U -DallowSnapshots=true -DparentVersion=[1.58.6-SNAPSHOT] versions:update-parent
...
[INFO] --- versions-maven-plugin:2.11.0:update-parent (default-cli) @ my-project ---
...
[INFO] Updating parent from 1.58.5-SNAPSHOT to 1.58.6-SNAPSHOT

Since release 2.12.0 (which contains #665 ), this is not possible anymore:

mvn -U -DallowSnapshots=true -DparentVersion=[1.58.6-SNAPSHOT] versions:update-parent
...
[INFO] --- versions-maven-plugin:2.12.0:update-parent (default-cli) @ my-project ---
...
[WARNING] Not updating version: could not resolve any versions

This is still a valid use case and should work as before.

The reason is, that UpdateParentMojo now calls the findLatestVersion method with parameter allowingSnapshots=false instead of null (as it was before) which leads to ignoring the allowSnapshots CLI property inside the findLatestVersion method of AbstractVersionsUpdaterMojo.

Probably providing null for allowingSnapshots method parameter was correct.

[rillner]

Just seen this duplicates #670