[MRESOLVER-376] Alt fix (#311)

Solve the mixup of Artifact used as key, as in case of relocation
A1 -> A2, when A1 descriptor is read, the result will have
A2 artifact set.

So, in code, we must go for "originally asked" A1 artifact, as
in case of relocation, the descriptor will hold A1 relocation
target, that is A2, causing endless loop.

---

https://issues.apache.org/jira/browse/MRESOLVER-376

maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/collect/bf/BfDependencyCollector.java

@@ -554,7 +554,14 @@ static class DescriptorResolutionResult {
 
         DescriptorResolutionResult(
                 VersionRangeResult rangeResult, Version version, ArtifactDescriptorResult descriptor) {
-            this(descriptor.getArtifact(), rangeResult);
+            // NOTE: In case of A1 -> A2 relocation this happens:
+            // ArtifactDescriptorResult read by ArtifactDescriptorResultReader for A1
+            // will return instance that will have artifact = A2 (as RelocatedArtifact).
+            // So to properly "key" this instance, we need to use "originally requested" A1 instead!
+            // In short:
+            // ArtifactDescriptorRequest.artifact != ArtifactDescriptorResult.artifact WHEN relocation in play
+            // otherwise (no relocation), they are EQUAL.
+            this(descriptor.getRequest().getArtifact(), rangeResult);
             this.descriptors.put(version, descriptor);
         }