[MNG-5180] Fixes dangling snapshot versions in metadata after merge

[patope]

If build number or timestamp have changed, snapshot versions needs to
be updated as well.

see:
https://github.com/apache/maven/blob/master/maven-resolver-provider/src/main/java/org/apache/maven/repository/internal/RemoteSnapshotMetadata.java#L134

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[michael-o]

I think this one is wrong because it has to work like versions. Test whether the collection contains if not, add it. You are replacing the list and not merging.

[michael-o]

I wonders me why this is pseudo-merged:

maven/maven-resolver-provider/src/main/java/org/apache/maven/repository/internal/RemoteSnapshotMetadata.java

Lines 121 to 138 in ecfff26

	Versioning versioning = recessive.getVersioning();
	if ( versioning != null )
	{
	for ( SnapshotVersion sv : versioning.getSnapshotVersions() )
	{
	String key = getKey( sv.getClassifier(), sv.getExtension() );
	if ( !versions.containsKey( key ) )
	{
	versions.put( key, sv );
	}
	}
	}
	if ( !legacyFormat )
	{
	metadata.getVersioning().setSnapshotVersions( new ArrayList<>( versions.values() ) );
	}
	}

The properly determine the diff, but throw away everything existent. Looks weird to me.

[michael-o]

Willing to merge when this one is addressed.

[patope]

I started to think is this correct fix after all.. wagon's merge-repo command uses this, but maybe this should be used for local repositories only. Maybe wagon should use RemoteSnapshotMetadata instead? Currently this is not possible due visibility limitations.

[michael-o]

I started to think is this correct fix after all.. wagon's merge-repo command uses this, but maybe this should be used for local repositories only. Maybe wagon should use RemoteSnapshotMetadata instead? Currently this is not possible due visibility limitations.

While I cannot clearly answer this question, why don't give it a try? Regardless of the Wagon problem, the behavior in Maven and Resolver should be consistent. Although, I do not know yet wether the key approach is logically correct.

[michael-o]

@kwin please pick up where @patope has left off in a new PR.

[michael-o]

Closing in favor of #681.