Provide a better message for erroneous values folder files

The task generateComposeResClass created an error message that didn't
help the user to understand the problem if files other than strings.xml
were in the values folder. This fix improves on the message so that users
can quickly fix the underlying issue.

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/resources/GenerateResClassTask.kt

@@ -96,10 +96,14 @@ internal abstract class GenerateResClassTask : DefaultTask() {
             return null
         }
 
-        if (typeString == "values" && file.name.equals("strings.xml", true)) {
-            val stringIds = getStringIds(file)
-            return stringIds.map { strId ->
-                ResourceItem(ResourceType.STRING, qualifiers, strId.asUnderscoredIdentifier(), path)
+        if (typeString == "values") {
+            if (file.name.equals("strings.xml", true)) {
+                val stringIds = getStringIds(file)
+                return stringIds.map { strId ->
+                    ResourceItem(ResourceType.STRING, qualifiers, strId.asUnderscoredIdentifier(), path)
+                }
+            } else {
+                error("Forbidden file name '${file.name}'! Only a file for string resources named 'strings.xml' is valid in the 'values' folder.")
             }
         }
 

gradle-plugins/compose/src/test/kotlin/org/jetbrains/compose/test/tests/integration/ResourcesTest.kt

@@ -119,7 +119,21 @@ class ResourcesTest : GradlePluginTestBase() {
             )
         }
 
+        file("src/commonMain/composeResources/values/strings.xml").renameTo(
+            file("src/commonMain/composeResources/values/colors.xml")
+        )
+        gradle("generateComposeResClass").checks {
+            check.logContains(
+                """
+                Forbidden file name 'colors.xml'! Only a file for string resources named 'strings.xml' is valid in the 'values' folder.
+            """.trimIndent()
+            )
+        }
+
         //restore defaults
+        file("src/commonMain/composeResources/values/colors.xml").renameTo(
+            file("src/commonMain/composeResources/values/strings.xml")
+        )
         file("src/commonMain/composeResources/string-us").renameTo(
             file("src/commonMain/composeResources/drawable-en")
         )