fix(redhat): don't return error if `root/buildinfo/content_manifests/…

…` contains files that are not `contentSets` files (#7912)

pkg/fanal/analyzer/buildinfo/content_manifest.go

@@ -31,6 +31,10 @@ func (a contentManifestAnalyzer) Analyze(_ context.Context, target analyzer.Anal
 		return nil, xerrors.Errorf("invalid content manifest: %w", err)
 	}
 
+	if len(manifest.ContentSets) == 0 {
+		return nil, nil
+	}
+
 	return &analyzer.AnalysisResult{
 		BuildInfo: &types.BuildInfo{
 			ContentSets: manifest.ContentSets,

pkg/fanal/analyzer/buildinfo/content_manifest_test.go

@@ -31,6 +31,11 @@ func Test_contentManifestAnalyzer_Analyze(t *testing.T) {
 				},
 			},
 		},
+		{
+			name:  "happy path for non-contentSets file",
+			input: "testdata/content_manifests/sbom-purl.json",
+			want:  nil,
+		},
 		{
 			name:    "broken json",
 			input:   "testdata/content_manifests/broken.json",

pkg/fanal/analyzer/buildinfo/testdata/content_manifests/sbom-purl.json

@@ -0,0 +1,9 @@
+{
+  "image_contents": {
+    "dependencies": [
+      {
+        "purl": "pkg:rpm/redhat/[email protected]?arch=src&checksum=sha256:f1ddea14d19746b867e69b48d128dd9c2d3e8cc021a5ea7b0674b48356ad3341&repository_id=rhel-9-base-source"
+      }
+    ]
+  }
+}