Set CommitInfo.commit in ChangeJson#toCommit

Change-Id: I285f767aafa1fa437cb96640ff90d55799ea46f9

Documentation/rest-api-changes.txt

@@ -389,6 +389,7 @@ default. Optional fields are:
             }
           },
           "commit": {
+            "commit": "184ebe53805e102605d11f6b143486d15c23a09c",
             "parents": [
               {
                 "commit": "1eee2c9d8f352483781e772f35dc586a69ff5646",
@@ -947,6 +948,7 @@ is included.
           }
         },
         "commit": {
+          "commit": "27cc4558b5a3d3387dd11ee2df7a117e7e581822",
           "parents": [
             {
               "commit": "b4003890dadd406d80222bf1ad8aca09a4876b70",
@@ -970,6 +972,7 @@ is included.
         }
       }
     }
+  }
 ----
 
 If the change cannot be rebased, e.g. due to conflicts, the response is
@@ -1325,6 +1328,7 @@ link:#current-commit[\{CURRENT_COMMIT\}] set.
           "ref": "refs/changes/79/1779/1",
           "fetch": {},
           "commit": {
+            "commit": "9adb9f4c7b40eeee0646e235de818d09164d7379",
             "parents": [
               {
                 "commit": "2d3176497a2747faed075f163707e57d9f961a1c",
@@ -1444,6 +1448,7 @@ link:#current-commit[\{CURRENT_COMMIT\}] set.
           "ref": "refs/changes/80/1780/1",
           "fetch": {},
           "commit": {
+            "commit": "1bd7c12a38854a2c6de426feec28800623f492c4",
             "parents": [
               {
                 "commit": "9adb9f4c7b40eeee0646e235de818d09164d7379",
@@ -2879,6 +2884,7 @@ is included.
           }
         },
         "commit": {
+          "commit": "27cc4558b5a3d3387dd11ee2df7a117e7e581822",
           "parents": [
             {
               "commit": "b4003890dadd406d80222bf1ad8aca09a4876b70",
@@ -2902,6 +2908,7 @@ is included.
         }
       }
     }
+  }
 ----
 
 If the revision cannot be rebased, e.g. due to conflicts, the response is

gerrit-server/src/main/java/com/google/gerrit/server/change/ChangeJson.java

@@ -1013,6 +1013,11 @@ public class ChangeJson {
       boolean addLinks) throws IOException {
     Project.NameKey project = ctl.getProject().getNameKey();
     CommitInfo info = new CommitInfo();
+
+    // TODO(fishywang): this is redundant with the map key, find a better way to provide the SHA-1
+    // for RevisionEvent.
+    info.commit = commit.name();
+
     info.parents = new ArrayList<>(commit.getParentCount());
     info.author = toGitPerson(commit.getAuthorIdent());
     info.committer = toGitPerson(commit.getCommitterIdent());