fixed inconsistencies with the dart-dio json_serializable string binary response types

Author: matthewnitschke-wk

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartDioClientCodegen.java

@@ -274,6 +274,9 @@ private void configureSerializationLibraryJsonSerializable(String srcFolder) {
         supportingFiles.add(new SupportingFile("serialization/json_serializable/deserialize.mustache", srcFolder,
                 "deserialize.dart"));
 
+        typeMapping.put("file", "Uint8List");
+        typeMapping.put("binary", "Uint8List");
+
         // most of these are defined in AbstractDartCodegen, we are overriding
         // just the binary / file handling
         languageSpecificPrimitives.add("Object");

modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/dio/DartDioClientCodegenTest.java

@@ -16,6 +16,10 @@
 
 package org.openapitools.codegen.dart.dio;
 
+import io.swagger.v3.oas.models.media.Content;
+import io.swagger.v3.oas.models.media.MediaType;
+import io.swagger.v3.oas.models.media.Schema;
+import io.swagger.v3.oas.models.responses.ApiResponse;
 import org.openapitools.codegen.*;
 import org.openapitools.codegen.config.CodegenConfigurator;
 import org.openapitools.codegen.languages.DartDioClientCodegen;
@@ -115,4 +119,25 @@ public void verifyDartDioGeneratorRuns() throws IOException {
         TestUtils.ensureContainsFile(files, output, "README.md");
         TestUtils.ensureContainsFile(files, output, "lib/src/api.dart");
     }
+
+    @Test(description = "json_serializable with binary response type (#20682)")
+    public void jsonSerializableBinaryResponseType() throws IOException {
+        final DefaultCodegen codegen = new DartDioClientCodegen();
+        codegen.additionalProperties().put(CodegenConstants.SERIALIZATION_LIBRARY, "json_serializable");
+        codegen.processOpts();
+
+        final MediaType binaryMediaType = new MediaType().schema(new Schema().type("string").format("binary"));
+
+        CodegenResponse zipResponse = codegen.fromResponse(
+                "200",
+                new ApiResponse().content(new Content().addMediaType("application/zip", binaryMediaType))
+        );
+        Assert.assertEquals(zipResponse.dataType, "Uint8List");
+
+        CodegenResponse streamResponse = codegen.fromResponse(
+                "200",
+                new ApiResponse().content(new Content().addMediaType("application/octet-stream", binaryMediaType))
+        );
+        Assert.assertEquals(streamResponse.dataType, "Uint8List");
+    }
 }