artifacts are downloaded serially in a single thread

[Eskibear]

Take a look at class AetherRepositoryConnector. For each artifact, there's a corresponding GetTask. And since there's a CountDownLatch, I believe the tasks are designed to run in parallel.
But, the code calls Runnable.run() directly, making it mono-threaded, see below:

aether-connector-okhttp/src/main/java/io/takari/aether/connector/AetherRepositoryConnector.java

Lines 299 to 306 in 2040c61

	for (ArtifactDownload download : artifactDownloads) {
	String resource = layout.getLocation(download.getArtifact(), false).getPath();
	GetTask<?> task = new GetTask<ArtifactTransfer>(resource, download.isExistenceCheck() ? null : download.getFile(), download.getChecksumPolicy(), latch, download, ARTIFACT);
	tasks.add(task);
	task.run();
	}
	await(latch);