synchronized(this) {
if(fetched) return;
if(!essential) return;
}
UOMDependencyFetcher f = manager.uom.fetchDependency(expectedHash, expectedLength, filename, executable,
new UOMDependencyFetcherCallback() {
@Override
public void onSuccess() {
synchronized(DependencyJarFetcher.this) {
if(fetched) return;