Eclipse Aether not resolving `LATEST` correctly

Eclipse Aether doesn't seem to return the correct release when I try to resolve a LATEST version:

val artifact = DefaultArtifact("org.testng:testng:LATEST")
val versionResult = system.resolveVrsion(session, VersionRequest(artifact, repositories, null))
println(versionResult)

produces:

6.9.8 @ maven (https://jcenter.bintray.com/, default, releases+snapshots)

However, 6.9.10 is the latest, and JCenter is reporting it correctly, both in the directory and also in the maven-metadata.xml:

<metadata>
  <groupId>org.testng</groupId>
  <artifactId>testng</artifactId>
  <version>6.9.10</version>
  <versioning>
    <latest>6.9.10</latest>
    <release>6.9.10</release>

Why am I getting 6.9.8 instead of 6.9.10?

Solution

There are two things which might the cause of your problem. First you assume that the magic word LATEST is supported by Aether and if i remember correctly (and looking into the code of Aether it is not supported). This means you should use a version range to get the latest.

Furthermore if you have a version range you need to call resolveVersionRange(...) instead of resolveVersion(..).

    String versionRange = "[0,)";

    Artifact artifact =
        new DefaultArtifact( "org.testng:testng:jar:" + versionRange );
    VersionRangeRequest rangeRequest = new VersionRangeRequest();
    rangeRequest.setArtifact( artifact );
    rangeRequest.setRepositories( remoteRepos );

    VersionRangeResult rangeResult = repository.resolveVersionRange( repositorySystemSession, rangeRequest );
    List<Version> versions = rangeResult.getVersions();

The above is a slightly modified version taken from a plugin i wrote. There is also a ctor of DefaultArtifact which contains only the appropriate parameters which might be a better alternative to use instead of concatenating the strings.