fix (JAVA NATIVE CLIENT): using anyOf with generic type lead to compile error

Author: Nicklas2751

modules/openapi-generator/src/main/resources/Java/libraries/native/anyof_model.mustache

@@ -191,7 +191,7 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
      * @return The actual instance of `{{{.}}}`
      * @throws ClassCastException if the instance is not `{{{.}}}`
      */
-    public {{{.}}} get{{{.}}}() throws ClassCastException {
+    public {{{.}}} get{{#sanitizeGeneric}}{{{.}}}{{/sanitizeGeneric}}() throws ClassCastException {
         return ({{{.}}})super.getActualInstance();
     }
 

modules/openapi-generator/src/main/resources/Java/libraries/native/oneof_model.mustache

@@ -224,7 +224,7 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
      * @return The actual instance of `{{{.}}}`
      * @throws ClassCastException if the instance is not `{{{.}}}`
      */
-    public {{{.}}} get{{{.}}}() throws ClassCastException {
+    public {{{.}}} get{{#sanitizeGeneric}}{{{.}}}{{/sanitizeGeneric}}() throws ClassCastException {
         return ({{{.}}})super.getActualInstance();
     }
 

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

@@ -151,18 +151,21 @@ public static void validateJavaSourceFiles(List<File> files) {
                         } catch (IOException ignored) {
 
                         }
-                        assertValidJavaSourceCode(fileContents);
+                        assertValidJavaSourceCode(fileContents, f.getAbsolutePath());
                     }
                 }
         );
     }
 
     public static void assertValidJavaSourceCode(String javaSourceCode) {
+        assertValidJavaSourceCode(javaSourceCode, null);
+    }
+    public static void assertValidJavaSourceCode(String javaSourceCode, String fileName) {
         ParserConfiguration config = new ParserConfiguration();
         config.setLanguageLevel(ParserConfiguration.LanguageLevel.JAVA_11);
         JavaParser parser = new JavaParser(config);
         ParseResult<CompilationUnit> parseResult = parser.parse(javaSourceCode);
-        assertTrue(parseResult.isSuccessful(), String.valueOf(parseResult.getProblems()));
+        assertTrue(parseResult.isSuccessful(), (fileName == null ? "" : "File " + fileName + ": ") + parseResult.getProblems());
     }
 
     public static void assertFileContains(Path path, String... lines) {

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

@@ -3592,4 +3592,48 @@ public void testClassesAreValidJavaOkHttpGson() {
                 "public some.pkg.B getsomepkgB() throws ClassCastException {"
         );
     }
+
+    @DataProvider(name = "allJavaClients")
+    public Object[][] allJavaClients() {
+        return new Object[][] {
+                { JavaClientCodegen.FEIGN },
+                { JavaClientCodegen.GOOGLE_API_CLIENT },
+                { JavaClientCodegen.JERSEY2 },
+                { JavaClientCodegen.JERSEY3 },
+                { JavaClientCodegen.NATIVE },
+                { JavaClientCodegen.OKHTTP_GSON },
+                { JavaClientCodegen.RESTEASY },
+                { JavaClientCodegen.RESTTEMPLATE },
+                { JavaClientCodegen.WEBCLIENT },
+                { JavaClientCodegen.RESTCLIENT },
+                { JavaClientCodegen.REST_ASSURED },
+                { JavaClientCodegen.RETROFIT_2 },
+                { JavaClientCodegen.VERTX },
+                { JavaClientCodegen.MICROPROFILE },
+                { JavaClientCodegen.APACHE }
+        };
+    }
+
+    @Test(dataProvider = "allJavaClients")
+    public void testClientWithAnyOfCausedCompileError(String client) {
+        if(JavaClientCodegen.MICROPROFILE.equals(client))
+        {
+            // MikroProfile currently does not support anyOf
+            return;
+        }
+
+        final Path output = newTempFolder();
+        final OpenAPI openAPI = new OpenAPIParser()
+                .readLocation("src/test/resources/3_1/java/petstore.yaml", null, new ParseOptions())
+                .getOpenAPI();
+        final JavaClientCodegen codegen = new JavaClientCodegen();
+        codegen.setOutputDir(output.toString());
+        codegen.setLibrary(client);
+
+        final ClientOptInput input = new ClientOptInput().openAPI(openAPI).config(codegen);
+
+        List<File> files = new DefaultGenerator().opts(input).generate();
+
+        validateJavaSourceFiles(files);
+    }
 }