modify enum template. field should be final. add testcase & sample updates. (#21019)

Author: takashno

modules/openapi-generator/src/main/resources/JavaSpring/enumClass.mustache

@@ -30,7 +30,7 @@
         {{/allowableValues}}
     {{/gson}}
 
-    private {{{dataType}}} value;
+    private final {{{dataType}}} value;
 
     {{{datatypeWithEnum}}}{{^datatypeWithEnum}}{{classname}}{{/datatypeWithEnum}}({{{dataType}}} value) {
       this.value = value;

modules/openapi-generator/src/main/resources/JavaSpring/enumOuterClass.mustache

@@ -31,7 +31,7 @@ public enum {{{datatypeWithEnum}}}{{^datatypeWithEnum}}{{{classname}}}{{/datatyp
   {{/-last}}{{#-last}};{{/-last}}{{/enumVars}}{{/allowableValues}}
   {{/gson}}
 
-  private {{{dataType}}} value;
+  private final {{{dataType}}} value;
 
   {{{datatypeWithEnum}}}{{^datatypeWithEnum}}{{{classname}}}{{/datatypeWithEnum}}({{{dataType}}} value) {
     this.value = value;

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

@@ -5432,4 +5432,17 @@ public void shouldDisableBuiltInValidationOptionByDefault() throws IOException {
                 .assertTypeAnnotations()
                 .containsWithName("Validated");
     }
+
+    @Test
+    public void testEnumFieldShouldBeFinal_issue21018() throws IOException {
+        SpringCodegen codegen = new SpringCodegen();
+        codegen.setLibrary(SPRING_BOOT);
+        Map<String, File> files = generateFiles(codegen, "src/test/resources/bugs/issue_21018.yaml");
+
+        JavaFileAssert.assertThat(files.get("SomeEnum.java"))
+                .fileContains("private final String value;");
+
+        JavaFileAssert.assertThat(files.get("SomeObject.java"))
+                .fileContains("private final String value");
+    }
 }

modules/openapi-generator/src/test/resources/bugs/issue_21018.yaml

@@ -0,0 +1,35 @@
+openapi: "3.0.3"
+info:
+  version: 1.0.0
+  title: test
+paths:
+  /test:
+    get:
+      summary: test
+      operationId: test
+      responses:
+        '200':
+          description: OK
+components:
+  schemas:
+    SomeEnum:
+      type: string
+      enum:
+        - Cat
+        - Dog
+      x-enum-varnames:
+        - CAT
+        - DOG
+    SomeObject:
+      type: object
+      properties:
+        name:
+          type: string
+        type:
+          type: string
+          enum:
+            - Cat
+            - Dog
+          x-enum-varnames:
+            - CAT
+            - DOG

samples/client/petstore/spring-cloud-deprecated/src/main/java/org/openapitools/model/Order.java

@@ -47,7 +47,7 @@ public enum StatusEnum {
 
     DELIVERED("delivered");
 
-    private String value;
+    private final String value;
 
     StatusEnum(String value) {
       this.value = value;

samples/client/petstore/spring-cloud-deprecated/src/main/java/org/openapitools/model/Pet.java

@@ -52,7 +52,7 @@ public enum StatusEnum {
 
     SOLD("sold");
 
-    private String value;
+    private final String value;
 
     StatusEnum(String value) {
       this.value = value;

samples/client/petstore/spring-cloud-feign-without-url/src/main/java/org/openapitools/model/Order.java

@@ -46,7 +46,7 @@ public enum StatusEnum {
 
     DELIVERED("delivered");
 
-    private String value;
+    private final String value;
 
     StatusEnum(String value) {
       this.value = value;

samples/client/petstore/spring-cloud-feign-without-url/src/main/java/org/openapitools/model/Pet.java

@@ -52,7 +52,7 @@ public enum StatusEnum {
 
     SOLD("sold");
 
-    private String value;
+    private final String value;
 
     StatusEnum(String value) {
       this.value = value;

samples/client/petstore/spring-cloud-tags/src/main/java/org/openapitools/model/Order.java

@@ -46,7 +46,7 @@ public enum StatusEnum {
 
     DELIVERED("delivered");
 
-    private String value;
+    private final String value;
 
     StatusEnum(String value) {
       this.value = value;

samples/client/petstore/spring-cloud-tags/src/main/java/org/openapitools/model/Pet.java

@@ -52,7 +52,7 @@ public enum StatusEnum {
 
     SOLD("sold");
 
-    private String value;
+    private final String value;
 
     StatusEnum(String value) {
       this.value = value;