Simplify MiddlemanAction interface

All creation goes through the static factory method.

PiperOrigin-RevId: 284178928
diff --git a/src/test/java/com/google/devtools/build/lib/actions/ArtifactTest.java b/src/test/java/com/google/devtools/build/lib/actions/ArtifactTest.java
index d03b769..8861ed9 100644
--- a/src/test/java/com/google/devtools/build/lib/actions/ArtifactTest.java
+++ b/src/test/java/com/google/devtools/build/lib/actions/ArtifactTest.java
@@ -24,6 +24,7 @@
 import com.google.devtools.build.lib.actions.ActionAnalysisMetadata.MiddlemanType;
 import com.google.devtools.build.lib.actions.Artifact.SourceArtifact;
 import com.google.devtools.build.lib.actions.ArtifactResolver.ArtifactResolverSupplier;
+import com.google.devtools.build.lib.actions.MutableActionGraph.ActionConflictException;
 import com.google.devtools.build.lib.actions.util.ActionsTestUtil;
 import com.google.devtools.build.lib.actions.util.LabelArtifactOwner;
 import com.google.devtools.build.lib.cmdline.Label;
@@ -156,9 +157,29 @@
     ArtifactRoot middleRoot =
         ArtifactRoot.middlemanRoot(scratch.dir("/foo"), scratch.dir("/foo/out"));
     Artifact middleman = ActionsTestUtil.createArtifact(middleRoot, "middleman");
-    actionGraph.registerAction(new MiddlemanAction(ActionsTestUtil.NULL_ACTION_OWNER,
-        ImmutableList.of(aHeader1, aHeader2, aHeader3), middleman, "desc",
-        MiddlemanType.AGGREGATING_MIDDLEMAN));
+    MiddlemanAction.create(
+        new ActionRegistry() {
+          @Override
+          public void registerAction(ActionAnalysisMetadata... actions) {
+            for (ActionAnalysisMetadata action : actions) {
+              try {
+                actionGraph.registerAction(action);
+              } catch (ActionConflictException e) {
+                throw new IllegalStateException(e);
+              }
+            }
+          }
+
+          @Override
+          public ActionLookupValue.ActionLookupKey getOwner() {
+            throw new UnsupportedOperationException();
+          }
+        },
+        ActionsTestUtil.NULL_ACTION_OWNER,
+        ImmutableList.of(aHeader1, aHeader2, aHeader3),
+        middleman,
+        "desc",
+        MiddlemanType.AGGREGATING_MIDDLEMAN);
     return collapsedList ? Lists.newArrayList(aHeader1, middleman) :
         Lists.newArrayList(aHeader1, aHeader2, middleman);
   }