Add support for Robot Comments

Extend the PostReview REST endpoint to support posting of robot
comments. For this ReviewInput got a new field that can contain a list
of robot comments. For reading robot comments new REST endpoints have
been added.

Robot comments are only supported with NoteDb, but not with ReviewDb.

Robot comments are always stored as JSON, even if notedb.writeJson is
set to false.

In NoteDb robot comments are not stored in the change meta ref but in
a separate refs/changes/XX/YYYY/robot-comments ref. By storing robot
comments in a separate ref we can delete robot comments without
rewriting the history of the change meta branch which is needed for
auditing and hence cannot be rewritten. Deletion of robot comments is
not implemented in this change, but we may want to support this later
as the amount and size of robot comments can be large.

Draft robot comments are not supported, but robot comments are always
published comments.

Change-Id: I2d8a5ca59e9a8b2c34863c54a3a9576599f69526
Signed-off-by: Edwin Kempin <ekempin@google.com>
diff --git a/Documentation/rest-api-changes.txt b/Documentation/rest-api-changes.txt
index 95fa1c9..88c1765 100644
--- a/Documentation/rest-api-changes.txt
+++ b/Documentation/rest-api-changes.txt
@@ -3904,6 +3904,102 @@
   }
 ----
 
+[[list-comments]]
+=== List Robot Comments
+--
+'GET /changes/link:#change-id[\{change-id\}]/revisions/link:#revision-id[\{revision-id\}]/robotcomments/'
+--
+
+Lists the link:config-robot-comments.html[robot comments] of a
+revision.
+
+As result a map is returned that maps the file path to a list of
+link:#robot-comment-info[RobotCommentInfo] entries. The entries in the
+map are sorted by file path.
+
+.Request
+----
+  GET /changes/myProject~master~I8473b95934b5732ac55d26311a706c9c2bde9940/revisions/674ac754f91e64a0efb8087e59a176484bd534d1/robotcomments/ HTTP/1.0
+----
+
+.Response
+----
+  HTTP/1.1 200 OK
+  Content-Disposition: attachment
+  Content-Type: application/json; charset=UTF-8
+
+  )]}'
+  {
+    "gerrit-server/src/main/java/com/google/gerrit/server/project/RefControl.java": [
+      {
+        "id": "TvcXrmjM",
+        "line": 23,
+        "message": "unused import",
+        "updated": "2016-02-26 15:40:43.986000000",
+        "author": {
+          "_account_id": 1000110,
+          "name": "Code Analyzer",
+          "email": "code.analyzer@example.com"
+        },
+        "robotId": "importChecker",
+        "robotRunId": "76b1375aa8626ea7149792831fe2ed85e80d9e04"
+      },
+      {
+        "id": "TveXwFiA",
+        "line": 49,
+        "message": "wrong indention",
+        "updated": "2016-02-26 15:40:45.328000000",
+        "author": {
+          "_account_id": 1000110,
+          "name": "Code Analyzer",
+          "email": "code.analyzer@example.com"
+        },
+        "robotId": "styleChecker",
+        "robotRunId": "5c606c425dd45184484f9d0a2ffd725a7607839b"
+      }
+    ]
+  }
+----
+
+[[get-robot-comment]]
+=== Get Robot Comment
+--
+'GET /changes/link:#change-id[\{change-id\}]/revisions/link:#revision-id[\{revision-id\}]/robotcomments/link:#comment-id[\{comment-id\}]'
+--
+
+Retrieves a link:config-robot-comments.html[robot comment] of a
+revision.
+
+.Request
+----
+  GET /changes/myProject~master~I8473b95934b5732ac55d26311a706c9c2bde9940/revisions/674ac754f91e64a0efb8087e59a176484bd534d1/robotcomments/TvcXrmjM HTTP/1.0
+----
+
+As response a link:#robot-comment-info[RobotCommentInfo] entity is
+returned that describes the robot comment.
+
+.Response
+----
+  HTTP/1.1 200 OK
+  Content-Disposition: attachment
+  Content-Type: application/json; charset=UTF-8
+
+  )]}'
+  {
+    "id": "TvcXrmjM",
+    "line": 23,
+    "message": "unused import",
+    "updated": "2016-02-26 15:40:43.986000000",
+    "author": {
+      "_account_id": 1000110,
+      "name": "Code Analyzer",
+      "email": "code.analyzer@example.com"
+    },
+    "robotId": "importChecker",
+    "robotRunId": "76b1375aa8626ea7149792831fe2ed85e80d9e04"
+  }
+----
+
 [[list-files]]
 === List Files
 --
@@ -5465,6 +5561,9 @@
 |`comments`               |optional|
 The comments that should be added as a map that maps a file path to a
 list of link:#comment-input[CommentInput] entities.
+|`robot_comments`         |optional|
+The robot comments that should be added as a map that maps a file path
+to a list of link:#robot-comment-input[RobotCommentInput] entities.
 |`strict_labels`          |`true` if not set|
 Whether all labels are required to be within the user's permitted ranges
 based on access controls. +
@@ -5591,6 +5690,29 @@
 certificate was provided, it is set to an empty object.
 |===========================
 
+[[robot-comment-info]]
+=== RobotCommentInfo
+The `RobotCommentInfo` entity contains information about a robot inline
+comment.
+
+`RobotCommentInfo` has the same fields as link:#[CommentInfo].
+In addition `RobotCommentInfo` has the following fields:
+
+[options="header",cols="1,^1,5"]
+|===========================
+|Field Name     ||Description
+|`robot_id`     ||The ID of the robot that generated this comment.
+|`robot_run_id` ||An ID of the run of the robot.
+|`url`          |optional|URL to more information.
+|===========================
+
+[[robot-comment-input]]
+=== RobotCommentInput
+The `RobotCommentInput` entity contains information for creating an inline
+robot comment.
+
+`RobotCommentInput` has the same fields as link:#[RobotCommentInfo].
+
 [[rule-input]]
 === RuleInput
 The `RuleInput` entity contains information to test a Prolog rule.