fix(fossid-webapp): Return empty PURL when artifact name is empty

The packageurl-jvm library throws MalformedPackageURLException when
the name component is empty. This can happen for snippets with empty
artifact names.
Return an empty string early when the name is blank.

This is a fixup for 334810d.

Signed-off-by: Nicolas Nobelis <nicolas.nobelis@bosch.com>

Author: nnobelis

plugins/scanners/fossid/src/main/kotlin/FossIdScanResults.kt

@@ -313,13 +313,21 @@ private fun Set<Snippet>.mapSnippetFindingsForFile(
         }
 
         val snippetProvenance = ArtifactProvenance(RemoteArtifact(url, Hash.NONE))
-        val purl = snippet.purl ?: PackageURLBuilder.aPackageURL()
-            .withType(urlToPackageType(url))
-            .withNamespace(snippet.author)
-            .withName(snippet.artifact)
-            .withVersion(snippet.version)
-            .build()
-            .canonicalize()
+        val purl = when {
+            snippet.purl != null -> snippet.purl
+
+            snippet.artifact.isNullOrEmpty() -> ""
+
+            else -> {
+                PackageURLBuilder.aPackageURL()
+                    .withType(urlToPackageType(url))
+                    .withNamespace(snippet.author)
+                    .withName(snippet.artifact)
+                    .withVersion(snippet.version)
+                    .build()
+                    .canonicalize()
+            }
+        }
 
         val additionalSnippetData = mutableMapOf(
             FossId.SNIPPET_DATA_ID to snippet.id.toString(),