add oneOf-default-case option for swift5 (#19094)

Co-authored-by: erokha <dev@erokha.com>

docs/generators/swift5.md

@@ -32,6 +32,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |mapFileBinaryToData|[WARNING] This option will be removed and enabled by default in the future once we've enhanced the code to work with `Data` in all the different situations. Map File and Binary to Data (default: false)| |false|
 |nonPublicApi|Generates code with reduced access modifiers; allows embedding elsewhere without exposing non-public API calls to consumers.(default: false)| |null|
 |objcCompatible|Add additional properties and methods for Objective-C compatibility (default: false)| |null|
+|oneOfUnknownDefaultCase|Add unknownDefault case to oneOf enum (default: false)| |false|
 |podAuthors|Authors used for Podspec| |null|
 |podDescription|Description used for Podspec| |null|
 |podDocumentationURL|Documentation URL used for Podspec| |null|

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift5ClientCodegen.java

@@ -67,6 +67,7 @@ public class Swift5ClientCodegen extends DefaultCodegen implements CodegenConfig
     public static final String LENIENT_TYPE_CAST = "lenientTypeCast";
     public static final String USE_SPM_FILE_STRUCTURE = "useSPMFileStructure";
     public static final String SWIFT_PACKAGE_PATH = "swiftPackagePath";
+    public static final String ONE_OF_UNKNOWN_DEFAULT_CASE = "oneOfUnknownDefaultCase";
     public static final String USE_CLASSES = "useClasses";
     public static final String USE_BACKTICK_ESCAPES = "useBacktickEscapes";
     public static final String GENERATE_MODEL_ADDITIONAL_PROPERTIES = "generateModelAdditionalProperties";
@@ -92,6 +93,7 @@ public class Swift5ClientCodegen extends DefaultCodegen implements CodegenConfig
     @Setter protected boolean swiftUseApiNamespace = false;
     @Setter protected boolean useSPMFileStructure = false;
     @Setter protected String swiftPackagePath = "Classes" + File.separator + "OpenAPIs";
+    @Setter protected boolean oneOfUnknownDefaultCase = false;
     @Setter protected boolean useClasses = false;
     @Setter protected boolean useBacktickEscapes = false;
     @Setter protected boolean generateModelAdditionalProperties = true;
@@ -292,6 +294,9 @@ public class Swift5ClientCodegen extends DefaultCodegen implements CodegenConfig
         cliOptions.add(new CliOption(GENERATE_MODEL_ADDITIONAL_PROPERTIES,
                 "Generate model additional properties (default: true)")
                 .defaultValue(Boolean.TRUE.toString()));
+        cliOptions.add(new CliOption(ONE_OF_UNKNOWN_DEFAULT_CASE,
+                "Add unknownDefault case to oneOf enum (default: false)")
+                .defaultValue(Boolean.FALSE.toString()));
 
         cliOptions.add(new CliOption(CodegenConstants.API_NAME_PREFIX, CodegenConstants.API_NAME_PREFIX_DESC));
         cliOptions.add(new CliOption(USE_SPM_FILE_STRUCTURE, "Use SPM file structure"
@@ -532,6 +537,11 @@ public class Swift5ClientCodegen extends DefaultCodegen implements CodegenConfig
             typeMapping.put("date", "Date");
         }
 
+        if (additionalProperties.containsKey(ONE_OF_UNKNOWN_DEFAULT_CASE)) {
+            setOneOfUnknownDefaultCase(convertPropertyToBooleanAndWriteBack(ONE_OF_UNKNOWN_DEFAULT_CASE));
+        }
+        additionalProperties.put(ONE_OF_UNKNOWN_DEFAULT_CASE, oneOfUnknownDefaultCase);
+
         if (additionalProperties.containsKey(USE_CLASSES)) {
             setUseClasses(convertPropertyToBooleanAndWriteBack(USE_CLASSES));
         }

modules/openapi-generator/src/main/resources/swift5/modelOneOf.mustache

@@ -2,6 +2,9 @@
     {{#oneOf}}
     case type{{.}}({{.}})
     {{/oneOf}}
+    {{#oneOfUnknownDefaultCase}}
+    case unknownDefault
+    {{/oneOfUnknownDefaultCase}}
 
     public func encode(to encoder: Encoder) throws {
         var container = encoder.singleValueContainer()
@@ -10,6 +13,10 @@
         case .type{{.}}(let value):
             try container.encode(value)
         {{/oneOf}}
+        {{#oneOfUnknownDefaultCase}}
+        case unknownDefault(let type):
+            try container.encodeNil()
+        {{/oneOfUnknownDefaultCase}}
         }
     }
 
@@ -25,7 +32,12 @@
             self = .type{{.}}(value)
         {{/oneOf}}
         } else {
+            {{#oneOfUnknownDefaultCase}}
+            self = .unknownDefault
+            {{/oneOfUnknownDefaultCase}}
+            {{^oneOfUnknownDefaultCase}}
             throw DecodingError.typeMismatch(Self.Type.self, .init(codingPath: decoder.codingPath, debugDescription: "Unable to decode instance of {{classname}}"))
+            {{/oneOfUnknownDefaultCase}}
         }
     }
 }

modules/openapi-generator/src/test/java/org/openapitools/codegen/options/Swift5OptionsProvider.java

@@ -100,6 +100,7 @@ public class Swift5OptionsProvider implements OptionsProvider {
                 .put(Swift5ClientCodegen.MAP_FILE_BINARY_TO_DATA, "false")
                 .put(Swift5ClientCodegen.USE_CUSTOM_DATE_WITHOUT_TIME, "false")
                 .put(Swift5ClientCodegen.VALIDATABLE, "true")
+                .put(Swift5ClientCodegen.ONE_OF_UNKNOWN_DEFAULT_CASE, "false")
                 .put(Swift5ClientCodegen.USE_CLASSES, "false")
                 .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();