[Kotlin] Fix explicitApi/nonPublicApi/generateOneOfAnyOfWrappers generation for kotlinx_serialization (#23796)

* Fix explicitApi & nonPublicApi generation for kotlinx_serialization

* Add missing explicitApi templates

Author: yzaoui

modules/openapi-generator/src/main/resources/kotlin-client/anyof_class.mustache

@@ -107,7 +107,7 @@ import java.io.IOException
 {{#anyOf}}
 {{^vendorExtensions.x-duplicated-data-type}}
     @JvmInline
-    {{#nonPublicApi}}internal {{/nonPublicApi}}{{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}value class {{#fnToValueClassName}}{{{dataType}}}{{/fnToValueClassName}}(val value: {{{dataType}}}) : {{classname}}
+    {{#explicitApi}}public {{/explicitApi}}value class {{#fnToValueClassName}}{{{dataType}}}{{/fnToValueClassName}}({{#nonPublicApi}}internal {{/nonPublicApi}}{{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}val value: {{{dataType}}}) : {{classname}}
 
 {{/vendorExtensions.x-duplicated-data-type}}
 {{/anyOf}}

modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/BigDecimalAdapter.kt.mustache

@@ -18,7 +18,7 @@ import java.math.BigDecimal
 {{#nonPublicApi}}internal {{/nonPublicApi}}{{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}object BigDecimalAdapter : KSerializer<BigDecimal> {
     override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor("BigDecimal", PrimitiveKind.STRING)
     override fun deserialize(decoder: Decoder): BigDecimal = BigDecimal(decoder.decodeString())
-    override fun serialize(encoder: Encoder, value: BigDecimal) = encoder.encodeString(value.toPlainString())
+    override fun serialize(encoder: Encoder, value: BigDecimal){{#explicitApi}}: Unit{{/explicitApi}} = encoder.encodeString(value.toPlainString())
 }
 {{/kotlinx_serialization}}
 {{#moshi}}

modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/Serializer.kt.mustache

@@ -134,7 +134,7 @@ import java.util.concurrent.atomic.AtomicLong
     private var isAdaptersInitialized = false
 
     @JvmStatic
-    val kotlinxSerializationAdapters: SerializersModule by lazy {
+    {{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}val kotlinxSerializationAdapters: SerializersModule by lazy {
         isAdaptersInitialized = true
         SerializersModule {
             contextual(BigDecimal::class, BigDecimalAdapter)
@@ -156,7 +156,7 @@ import java.util.concurrent.atomic.AtomicLong
         }
     }
 
-    var kotlinxSerializationAdaptersConfiguration: SerializersModuleBuilder.() -> Unit = {}
+    {{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}var kotlinxSerializationAdaptersConfiguration: SerializersModuleBuilder.() -> Unit = {}
         set(value) {
             check(!isAdaptersInitialized) {
                 "Cannot configure kotlinxSerializationAdaptersConfiguration after kotlinxSerializationAdapters has been initialized."
@@ -167,7 +167,7 @@ import java.util.concurrent.atomic.AtomicLong
     private var isJsonInitialized = false
 
     @JvmStatic
-    val kotlinxSerializationJson: Json by lazy {
+    {{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}val kotlinxSerializationJson: Json by lazy {
         isJsonInitialized = true
         Json {
             serializersModule = kotlinxSerializationAdapters
@@ -179,7 +179,7 @@ import java.util.concurrent.atomic.AtomicLong
         }
     }
 
-    var kotlinxSerializationJsonConfiguration: JsonBuilder.() -> Unit = {}
+    {{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}var kotlinxSerializationJsonConfiguration: JsonBuilder.() -> Unit = {}
         set(value) {
             check(!isJsonInitialized) {
                 "Cannot configure kotlinxSerializationJsonConfiguration after kotlinxSerializationJson has been initialized."

modules/openapi-generator/src/main/resources/kotlin-client/oneof_class.mustache

@@ -169,7 +169,7 @@ import java.io.IOException
 {{#oneOf}}
 {{^vendorExtensions.x-duplicated-data-type}}
     @JvmInline
-    {{#nonPublicApi}}internal {{/nonPublicApi}}{{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}value class {{#fnToValueClassName}}{{{dataType}}}{{/fnToValueClassName}}(val value: {{{dataType}}}) : {{classname}}
+    {{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}value class {{#fnToValueClassName}}{{{dataType}}}{{/fnToValueClassName}}({{#nonPublicApi}}internal {{/nonPublicApi}}{{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}val value: {{{dataType}}}) : {{classname}}
 
 {{/vendorExtensions.x-duplicated-data-type}}
 {{/oneOf}}

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

@@ -685,6 +685,57 @@ public void anyOfPrimitiveKotlinxSerialization() throws IOException {
         TestUtils.assertFileContains(parentModelKt, "val id: ObjectWithComplexAnyOfId?");
     }
 
+    @Test(description = "generate oneOf/anyOf wrappers with explicit API mode using kotlinx_serialization")
+    public void oneOfAnyOfKotlinxSerializationExplicitApi() throws IOException {
+        File output = generateKotlinxOneOfAnyOf(new HashMap<>() {{ put(KotlinClientCodegen.EXPLICIT_API, true); }});
+        // value class nested inside sealed interface: public is valid, internal is not
+        TestUtils.assertFileContains(modelPath(output, "ObjectWithComplexOneOfId"),
+                "public value class StringValue(public val value: kotlin.String) : ObjectWithComplexOneOfId");
+        TestUtils.assertFileContains(modelPath(output, "ObjectWithComplexAnyOfId"),
+                "public value class StringValue(public val value: kotlin.String) : ObjectWithComplexAnyOfId");
+    }
+
+    @Test(description = "generate oneOf/anyOf wrappers with non-public API mode using kotlinx_serialization")
+    public void oneOfAnyOfKotlinxSerializationNonPublicApi() throws IOException {
+        File output = generateKotlinxOneOfAnyOf(new HashMap<>() {{ put(CodegenConstants.NON_PUBLIC_API, true); }});
+        // Kotlin doesn't allow internal subclasses of internal interfaces, make sure subclasses are generated correctly
+        TestUtils.assertFileContains(modelPath(output, "ObjectWithComplexOneOfId"),
+                "internal sealed interface ObjectWithComplexOneOfId");
+        TestUtils.assertFileNotContains(modelPath(output, "ObjectWithComplexOneOfId"),
+                "internal value class StringValue");
+        TestUtils.assertFileContains(modelPath(output, "ObjectWithComplexOneOfId"),
+                "value class StringValue(internal val value: kotlin.String) : ObjectWithComplexOneOfId");
+        TestUtils.assertFileContains(modelPath(output, "ObjectWithComplexAnyOfId"),
+                "internal sealed interface ObjectWithComplexAnyOfId");
+        TestUtils.assertFileNotContains(modelPath(output, "ObjectWithComplexAnyOfId"),
+                "internal value class StringValue");
+        TestUtils.assertFileContains(modelPath(output, "ObjectWithComplexAnyOfId"),
+                "value class StringValue(internal val value: kotlin.String) : ObjectWithComplexAnyOfId");
+    }
+
+    private File generateKotlinxOneOfAnyOf(Map<String, Object> extraProps) throws IOException {
+        File output = Files.createTempDirectory("test").toFile();
+        output.deleteOnExit();
+        Map<String, Object> props = new HashMap<>();
+        props.put(CodegenConstants.SERIALIZATION_LIBRARY, "kotlinx_serialization");
+        props.put(GENERATE_ONEOF_ANYOF_WRAPPERS, true);
+        props.putAll(extraProps);
+        new DefaultGenerator()
+                .opts(new CodegenConfigurator()
+                        .setGeneratorName("kotlin")
+                        .setLibrary("jvm-retrofit2")
+                        .setAdditionalProperties(props)
+                        .setInputSpec("src/test/resources/3_0/issue_19942.json")
+                        .setOutputDir(output.getAbsolutePath().replace("\\", "/"))
+                        .toClientOptInput())
+                .generate();
+        return output;
+    }
+
+    private static Path modelPath(File output, String modelName) {
+        return Paths.get(output + "/src/main/kotlin/org/openapitools/client/models/" + modelName + ".kt");
+    }
+
     @Test(description = "generate polymorphic jackson model")
     public void polymorphicJacksonSerialization() throws IOException {
         File output = Files.createTempDirectory("test").toFile();