Add REST endpoint to list the commits that are integrated by a merge

In a later step we want to display this list in the change screen if a
merge commit is reviewed. This allows reviewers to see which commits
are being integrated by accepting the merge commit.

Change-Id: Ic4fc31608fd645ae6f55afc6ce24215c7c393404
Signed-off-by: Edwin Kempin <ekempin@google.com>

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/api/changes/RevisionApi.java

@@ -17,6 +17,7 @@ package com.google.gerrit.extensions.api.changes;
 import com.google.gerrit.extensions.client.SubmitType;
 import com.google.gerrit.extensions.common.ActionInfo;
 import com.google.gerrit.extensions.common.CommentInfo;
+import com.google.gerrit.extensions.common.CommitInfo;
 import com.google.gerrit.extensions.common.FileInfo;
 import com.google.gerrit.extensions.common.MergeableInfo;
 import com.google.gerrit.extensions.common.TestSubmitRuleInput;
@@ -72,6 +73,33 @@ public interface RevisionApi {
   SubmitType submitType() throws RestApiException;
   SubmitType testSubmitType(TestSubmitRuleInput in) throws RestApiException;
 
+  MergeListRequest getMergeList() throws RestApiException;
+
+  abstract class MergeListRequest {
+    private boolean addLinks;
+    private int uninterestingParent = 1;
+
+    public abstract List<CommitInfo> get() throws RestApiException;
+
+    public MergeListRequest withLinks() {
+      this.addLinks = true;
+      return this;
+    }
+
+    public MergeListRequest withUninterestingParent(int uninterestingParent) {
+      this.uninterestingParent = uninterestingParent;
+      return this;
+    }
+
+    public boolean getAddLinks() {
+      return addLinks;
+    }
+
+    public int getUninterestingParent() {
+      return uninterestingParent;
+    }
+  }
+
   /**
    * A default implementation which allows source compatibility
    * when adding new methods to the interface.
@@ -217,5 +245,10 @@ public interface RevisionApi {
         throws RestApiException {
       throw new NotImplementedException();
     }
+
+    @Override
+    public MergeListRequest getMergeList() throws RestApiException {
+      throw new NotImplementedException();
+    }
   }
 }