[kotlin] do not HTML-escape property names in generated KDoc @PARAM (#25028)

Kotlin wraps a property name that is not a valid identifier in back-ticks,
for example `2ndField` for a schema property named "2nd_field". The model
templates rendered that name with a double-brace Mustache tag, which HTML
escapes it, so the generated KDoc read:

    @PARAM `2ndField` An optional property ...

Switch the two affected templates to a triple-brace tag, matching what
kotlin-client, kotlin-server, ktor2 and jaxrs-spec already do.

No committed sample changes, because no existing kotlin-spring or
kotlin-vertx sample has a property name that needs back-ticks. The new
test uses param-json-property.yaml, which does.


Claude-Session: https://claude.ai/code/session_01VBn7VWUxZL6mTUbg21xNjm

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: rvlasveld

modules/openapi-generator/src/main/resources/kotlin-spring/dataClass.mustache

@@ -1,10 +1,10 @@
 /**
  * {{{description}}}
 {{#requiredVars}}
- * @param {{name}} {{{description}}}
+ * @param {{{name}}} {{{description}}}
 {{/requiredVars}}
 {{#optionalVars}}
- * @param {{name}} {{{description}}}
+ * @param {{{name}}} {{{description}}}
 {{/optionalVars}}
  */{{#discriminator}}
 {{>typeInfoAnnotation}}{{/discriminator}}

modules/openapi-generator/src/main/resources/kotlin-vertx-server/data_class.mustache

@@ -9,7 +9,7 @@ import com.fasterxml.jackson.annotation.JsonInclude
 /**
  * {{{description}}}
 {{#vars}}
- * @param {{name}} {{{description}}}
+ * @param {{{name}}} {{{description}}}
 {{/vars}}
  */
 {{#parcelizeModels}}

modules/openapi-generator/src/test/java/org/openapitools/codegen/kotlin/spring/KotlinSpringServerCodegenTest.java

@@ -7797,6 +7797,20 @@ public void paramJsonPropertyAnnotationWithDigitStartingPropertyName() throws IO
         );
     }
 
+    @Test(description = "KDoc @param must name the property literally, without HTML-escaping its back-ticks")
+    public void kdocParamNameIsNotHtmlEscaped() throws IOException {
+        Map<String, File> files = generateFromContract(
+                "src/test/resources/3_0/kotlin/param-json-property.yaml"
+        );
+
+        File itemFile = files.get("Item.kt");
+        assertThat(itemFile).isNotNull();
+        // "2nd_field" is not a valid Kotlin identifier, so the property is declared as `2ndField`.
+        // The KDoc must carry those back-ticks as written rather than as HTML entities.
+        assertFileNotContains(itemFile.toPath(), "&#x60;");
+        assertFileContains(itemFile.toPath(), "@param `2ndField` ");
+    }
+
 
     /**
      * Regression test for https://github.com/OpenAPITools/openapi-generator/issues/24139