[analyzer] Update messages and lint docs for downstream status

Change-Id: Ie4e057956dba0e568fa7fa6497ce42922207a382
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/414440
Commit-Queue: Brian Wilkerson <[email protected]>
Reviewed-by: Samuel Rawlins <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: parlough

pkg/analyzer/messages.yaml

@@ -5137,7 +5137,8 @@ CompileTimeErrorCode:
 
       #### Common fixes
 
-      If the value can be computed without storing it in a field, then try using a getter or a method:
+      If the value can be computed without storing it in a field, then try
+      using a getter or a method:
 
       ```dart
       extension E on String {
@@ -5147,15 +5148,17 @@ CompileTimeErrorCode:
       }
       ```
 
-      If the value must be stored, but is the same for every instance, try using a static field:
+      If the value must be stored, but is the same for every instance,
+      try using a static field:
 
       ```dart
       extension E on String {
         static String s = '';
       }
       ```
 
-      If each instance needs to have its own value stored, then try using a getter and setter pair backed by a static Expando:
+      If each instance needs to have its own value stored, then try
+      using a getter and setter pair backed by a static `Expando`:
 
       ```dart
       extension E on SomeType {

pkg/linter/lib/src/lint_codes.g.dart

@@ -1938,6 +1938,7 @@ class LinterLintCode extends LintCode {
     LintNames.use_null_aware_elements,
     "Use the null-aware marker '?' rather than a null check via an 'if'.",
     correctionMessage: "Try using '?'.",
+    hasPublishedDocs: true,
   );
 
   static const LintCode use_raw_strings = LinterLintCode(

pkg/linter/messages.yaml

@@ -4527,7 +4527,7 @@ LintCode:
       **DO** use Flutter TODO format.
 
       From the [Flutter
-      docs](https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#comments):
+      docs](https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#comments):
 
       > TODOs should include the string TODO in all caps, followed by the GitHub
       username of the person with the best context about the problem referenced by the
@@ -14226,7 +14226,7 @@ LintCode:
     state:
       stable: "3.8"
     categories: [brevity, style]
-    hasPublishedDocs: false
+    hasPublishedDocs: true
     documentation: |-
       #### Description
 

pkg/linter/tool/machine/rules.json

@@ -1091,7 +1091,7 @@
     "incompatible": [],
     "sets": [],
     "fixStatus": "hasFix",
-    "details": "**DO** use Flutter TODO format.\n\nFrom the [Flutter\ndocs](https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#comments):\n\n> TODOs should include the string TODO in all caps, followed by the GitHub\nusername of the person with the best context about the problem referenced by the\nTODO in parenthesis. A TODO is not a commitment that the person referenced will\nfix the problem, it is intended to be the person with enough context to explain\nthe problem. Thus, when you create a TODO, it is almost always your username\nthat is given.\n\n**GOOD:**\n```dart\n// TODO(username): message.\n// TODO(username): message, https://URL-to-issue.\n```",
+    "details": "**DO** use Flutter TODO format.\n\nFrom the [Flutter\ndocs](https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#comments):\n\n> TODOs should include the string TODO in all caps, followed by the GitHub\nusername of the person with the best context about the problem referenced by the\nTODO in parenthesis. A TODO is not a commitment that the person referenced will\nfix the problem, it is intended to be the person with enough context to explain\nthe problem. Thus, when you create a TODO, it is almost always your username\nthat is given.\n\n**GOOD:**\n```dart\n// TODO(username): message.\n// TODO(username): message, https://URL-to-issue.\n```",
     "sinceDartSdk": "2.1"
   },
   {
@@ -2673,7 +2673,7 @@
     "categories": [
       "style"
     ],
-    "state": "experimental",
+    "state": "stable",
     "incompatible": [],
     "sets": [],
     "fixStatus": "hasFix",
@@ -3143,6 +3143,20 @@
     "details": "Where possible, use already defined const values.\n\n**BAD:**\n```dart\nconst Duration(seconds: 0);\n```\n\n**GOOD:**\n```dart\nDuration.zero;\n```",
     "sinceDartSdk": "2.13"
   },
+  {
+    "name": "use_null_aware_elements",
+    "description": "If-elements testing for null can be replaced with null-aware elements.",
+    "categories": [
+      "brevity",
+      "style"
+    ],
+    "state": "stable",
+    "incompatible": [],
+    "sets": [],
+    "fixStatus": "hasFix",
+    "details": "Where possible, use null-aware elements in collection literals.\n\n**BAD:**\n```dart\nf(String? key) => {if (key != null) key: \"value\"};\n```\n\n**GOOD:**\n```dart\nf(String? key) => {?key: \"value\"};\n```",
+    "sinceDartSdk": "3.8"
+  },
   {
     "name": "use_raw_strings",
     "description": "Use raw string to avoid escapes.",
@@ -3289,4 +3303,4 @@
     "details": "**DON'T** assign to `void`.\n\n**BAD:**\n```dart\nclass A<T> {\n  T value;\n  void test(T arg) { }\n}\n\nvoid main() {\n  A<void> a = A<void>();\n  a.value = 1; // LINT\n  a.test(1); // LINT\n}\n```",
     "sinceDartSdk": "2.0"
   }
-]
+]