Serverless products should not allow versioning (#2920)

* Serverless products should not allow versioning

* Fix test and improve error message

* Remove versions from serverless applicability declarations

Author: cotti

docs/syntax/applies.md

@@ -314,9 +314,9 @@ apm_agent_java: beta 1.0+
 edot_dotnet: preview 1.0+
 edot_python:
 edot_node: ga 1.0+
-elasticsearch: preview 9.0+
-security: removed 9.0
-observability: deprecated 9.0+
+elasticsearch: preview
+security: removed
+observability: deprecated
 ```
 
 ### In-text example

src/Elastic.Documentation/AppliesTo/ApplicableToYamlConverter.cs

@@ -150,13 +150,15 @@ private static void AssignDeploymentType(Dictionary<object, object?> dictionary,
 			applicableTo.Deployment = DeploymentApplicability.All;
 		else if (deploymentType is string deploymentTypeString)
 		{
-			var av = AppliesCollection.TryParse(deploymentTypeString, diagnostics, out var a) ? a : null;
+			var applies = AppliesCollection.TryParse(deploymentTypeString, diagnostics, out var a) ? a : null;
+			if (applies is not null)
+				ValidateApplicabilityCollection("ess", applies, diagnostics);
 			applicableTo.Deployment = new DeploymentApplicability
 			{
-				Ece = av,
-				Eck = av,
-				Ess = av,
-				Self = av
+				Ece = applies,
+				Eck = applies,
+				Ess = applies,
+				Self = applies
 			};
 		}
 		else if (deploymentType is Dictionary<object, object?> deploymentDictionary)
@@ -193,12 +195,14 @@ private static void AssignServerless(Dictionary<object, object?> dictionary, App
 			applicableTo.Serverless = ServerlessProjectApplicability.All;
 		else if (serverless is string serverlessString)
 		{
-			var av = AppliesCollection.TryParse(serverlessString, diagnostics, out var a) ? a : null;
+			var applies = AppliesCollection.TryParse(serverlessString, diagnostics, out var a) ? a : null;
+			if (applies is not null)
+				ValidateApplicabilityCollection("serverless", applies, diagnostics);
 			applicableTo.Serverless = new ServerlessProjectApplicability
 			{
-				Elasticsearch = av,
-				Observability = av,
-				Security = av
+				Elasticsearch = applies,
+				Observability = applies,
+				Security = applies
 			};
 		}
 		else if (serverless is Dictionary<object, object?> serverlessDictionary)
@@ -322,6 +326,9 @@ private static bool TryGetProductApplicability(Dictionary<object, object?> dicti
 		return true;
 	}
 
+	private static readonly HashSet<string> VersionlessKeys =
+		["ess", "ech", "serverless", "elasticsearch", "observability", "security"];
+
 	private static bool TryGetApplicabilityOverTime(Dictionary<object, object?> dictionary, string key, List<(Severity, string)> diagnostics,
 		out AppliesCollection? availability)
 	{
@@ -345,6 +352,15 @@ private static void ValidateApplicabilityCollection(string key, AppliesCollectio
 	{
 		var items = collection.ToList();
 
+		// Rule: Versionless products cannot have version specifications
+		if (VersionlessKeys.Contains(key))
+		{
+			if (items.Any(a => a.Version is not null && a.Version != AllVersionsSpec.Instance))
+				diagnostics.Add((Severity.Error,
+					$"Can't specify a version for '{key}' because this product is not versioned. Remove the version, or use 'stack:' for version-specific requirements."));
+			return;
+		}
+
 		// Rule: Only one version declaration per lifecycle
 		var lifecycleGroups = items.GroupBy(a => a.Lifecycle).ToList();
 		var lifecyclesWithMultipleVersions = lifecycleGroups

tests/authoring/Applicability/AppliesToDirective.fs

@@ -15,9 +15,9 @@ type ``piggy back off yaml formatting`` () =
     static let markdown = Setup.Markdown """
 ```yaml {applies_to}
 serverless:
-  security: ga 9.0.0
-  elasticsearch: beta 9.1.0
-  observability: removed 9.2.0
+  security: ga
+  elasticsearch: beta
+  observability: removed
 ```
 """
 
@@ -28,19 +28,19 @@ serverless:
 
         directives |> appliesToDirective (ApplicableTo(
             Serverless=ServerlessProjectApplicability(
-                Security=AppliesCollection.op_Explicit "ga 9.0.0",
-                Elasticsearch=AppliesCollection.op_Explicit "beta 9.1.0",
-                Observability=AppliesCollection.op_Explicit "removed 9.2.0"
+                Security=AppliesCollection.op_Explicit "ga",
+                Elasticsearch=AppliesCollection.op_Explicit "beta",
+                Observability=AppliesCollection.op_Explicit "removed"
             )
         ))
 
 type ``plain block`` () =
     static let markdown = Setup.Markdown """
 ```{applies_to}
 serverless:
-  security: ga 9.0.0
-  elasticsearch: beta 9.1.0
-  observability: removed 9.2.0
+  security: ga
+  elasticsearch: beta
+  observability: removed
 apm_agent_dotnet: ga 9.0
 apm_agent_node: ga 10.0
 ```
@@ -53,9 +53,9 @@ apm_agent_node: ga 10.0
 
         directives |> appliesToDirective (ApplicableTo(
             Serverless=ServerlessProjectApplicability(
-                Security=AppliesCollection.op_Explicit "ga 9.0.0",
-                Elasticsearch=AppliesCollection.op_Explicit "beta 9.1.0",
-                Observability=AppliesCollection.op_Explicit "removed 9.2.0"
+                Security=AppliesCollection.op_Explicit "ga",
+                Elasticsearch=AppliesCollection.op_Explicit "beta",
+                Observability=AppliesCollection.op_Explicit "removed"
             ),
             ProductApplicability=ProductApplicability(
                 ApmAgentDotnet=AppliesCollection.op_Explicit "ga 9.0",