fix: do not generate no arg constructor with non nullable fields

Author: pkernevez

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

@@ -89,11 +89,13 @@ public {{>sealed}}class {{classname}}{{#parent}} extends {{{parent}}}{{/parent}}
   {{/isContainer}}
   {{/vars}}
   {{#vendorExtensions.x-java-no-args-constructor}}
+  {{^openApiNullable}}
 
-  public {{classname}}() {
-    super();
-  }
-  {{/vendorExtensions.x-java-no-args-constructor}}
+      public {{classname}}() {
+      super();
+      }
+  {{/openApiNullable}}
+{{/vendorExtensions.x-java-no-args-constructor}}
   {{^lombok.Data}}
   {{^lombok.RequiredArgsConstructor}}
   {{#generatedConstructorWithRequiredArgs}}

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

@@ -2877,11 +2877,12 @@ public void shouldUseTheSameTagNameForTheInterfaceAndTheMethod_issue11570() thro
     }
 
     @Test
-    public void shouldGenerateConstructorWithOnlyRequiredParameters() throws IOException {
+    public void shouldGenerateConstructorWithOnlyRequiredParametersAndNoArgConstructorWithOpenApiNullable() throws IOException {
         final Map<String, File> output = generateFromContract(
                 "src/test/resources/3_0/spring/issue_9789.yml",
                 SPRING_BOOT,
-                Map.of(GENERATE_CONSTRUCTOR_WITH_ALL_ARGS, "false")
+                Map.of(GENERATE_CONSTRUCTOR_WITH_ALL_ARGS, "false",
+                       OPENAPI_NULLABLE, "false")
         );
 
         JavaFileAssert.assertThat(output.get("ObjectWithNoRequiredParameter.java")).hasNoConstructor("String");
@@ -2899,6 +2900,30 @@ public void shouldGenerateConstructorWithOnlyRequiredParameters() throws IOExcep
                 .bodyContainsLines("super(param2, param3)", "this.param6 = param6");
     }
 
+    @Test
+    public void shouldGenerateConstructorWithOnlyRequiredParametersWhenNoOpenapiNullable() throws IOException {
+        final Map<String, File> output = generateFromContract(
+                "src/test/resources/3_0/spring/issue_9789.yml",
+                SPRING_BOOT,
+                Map.of(GENERATE_CONSTRUCTOR_WITH_ALL_ARGS, "false",
+                       OPENAPI_NULLABLE, "true")
+        );
+
+        JavaFileAssert.assertThat(output.get("ObjectWithNoRequiredParameter.java")).hasNoConstructor("String");
+
+        JavaFileAssert.assertThat(output.get("ObjectWithRequiredParameter.java")).hasNoConstructor();
+        JavaFileAssert.assertThat(output.get("ObjectWithRequiredParameter.java")).assertConstructor("String", "String")
+                .hasParameter("param2").toConstructor()
+                .hasParameter("param3");
+
+        JavaFileAssert.assertThat(output.get("ObjectWithInheritedRequiredParameter.java")).hasNoConstructor();
+        JavaFileAssert.assertThat(output.get("ObjectWithInheritedRequiredParameter.java")).assertConstructor("Integer", "String", "String")
+                .hasParameter("param2").toConstructor()
+                .hasParameter("param3").toConstructor()
+                .hasParameter("param6").toConstructor()
+                .bodyContainsLines("super(param2, param3)", "this.param6 = param6");
+    }
+
     private Map<String, File> generateFromContract(String url, String library) throws IOException {
         return generateFromContract(url, library, new HashMap<>());
     }
@@ -4958,6 +4983,7 @@ public void testLombokAnnotations() throws IOException {
                 .hasNoMethod("setName")
         ;
         additionalProperties.put(AbstractJavaCodegen.ADDITIONAL_MODEL_TYPE_ANNOTATIONS, "@lombok.ToString");
+        additionalProperties.put(AbstractJavaCodegen.OPENAPI_NULLABLE, "false");
         output = generateFromContract("src/test/resources/3_0/petstore.yaml", SPRING_BOOT, additionalProperties);
         JavaFileAssert.assertThat(output.get("Pet.java"))
                 .assertConstructor().toFileAssert()