Fix caching bug when retrieving artifact

This commit fixes a caching bug when retrieving an artifact. The ToString() value of Product should be used rather than just ProductName, as the ToString() value will also take into account the SubProductName, if there's a SubProduct set.

Author: russcam

src/Elastic.Stack.Artifacts/ElasticVersion.cs

@@ -21,8 +21,8 @@ protected ElasticVersion(string version, ArtifactBuildState state, string buildH
 		private readonly ConcurrentDictionary<string, Artifact> _resolved = new ConcurrentDictionary<string, Artifact>();
 		public Artifact Artifact(Product product)
 		{
-			Artifact artifact;
-			if (_resolved.TryGetValue(product.ProductName, out artifact))
+			var cacheKey = product.ToString();
+			if (_resolved.TryGetValue(cacheKey, out var artifact))
 				return artifact;
 			switch (ArtifactBuildState)
 			{
@@ -39,7 +39,7 @@ public Artifact Artifact(Product product)
 					throw new ArgumentOutOfRangeException(nameof(ArtifactBuildState), $"{ArtifactBuildState} not expected here");
 			}
 
-			_resolved.TryAdd(product.ProductName, artifact);
+			_resolved.TryAdd(cacheKey, artifact);
 
 			return artifact;
 		}