diff --git a/java/src/main/java/org/softwareheritage/graph/SwhUnidirectionalGraph.java b/java/src/main/java/org/softwareheritage/graph/SwhUnidirectionalGraph.java
--- a/java/src/main/java/org/softwareheritage/graph/SwhUnidirectionalGraph.java
+++ b/java/src/main/java/org/softwareheritage/graph/SwhUnidirectionalGraph.java
@@ -210,4 +210,12 @@
     public SwhGraphProperties getProperties() {
         return properties;
     }
+
+    public ImmutableGraph underlyingGraph() {
+        return graph;
+    }
+
+    public ArcLabelledImmutableGraph underlyingLabelledGraph() {
+        return labelledGraph;
+    }
 }