improvement: Support minimal definitions for tagged unions

Previously, this library only supported `Id.NAME` and `Id.CLASS` for `@JsonTypeInfo`, however, since inception, `Id.MINIMAL_CLASS` and `Id.SIMPLE_NAME` have been introduced, which allows us to write less redundant code, and have a more compact representation.

While `Id.SIMPLE_NAME` is not in Jackson bom 2.15.2 (which is what this project uses), `Id.MINIMAL_CLASS` is.

I use Jackson 2.18+, and would like to use the `SIMPLE_NAME` representation, instead of manually annotating thousands of classes, I would prefer to support the minimal definition for sealed interfaces/classes.

This commit makes a more forward compatible method of determining if a tagged union is being used, and instead of only allowing certain uses, it, instead, disallows known non-functional usages.

Author: Nthalk

typescript-generator-core/src/main/java/cz/habarta/typescript/generator/parser/Jackson2Parser.java

@@ -108,11 +108,11 @@ public Jackson2Parser create(Settings settings, TypeProcessor commonTypeProcesso
     }
 
     public static class JaxbParserFactory extends Jackson2ParserFactory {
-        
+
         public JaxbParserFactory() {
             super(true);
         }
-        
+
     }
 
     private final ObjectMapper objectMapper = new ObjectMapper();
@@ -423,12 +423,22 @@ private Type processIdentity(Type propertyType, BeanProperty beanProperty) {
     private boolean isTaggedUnion(Pair<Class<?>, JsonTypeInfo> classWithJsonTypeInfo) {
         final Class<?> cls = classWithJsonTypeInfo.getValue1();
         final JsonTypeInfo jsonTypeInfo = classWithJsonTypeInfo.getValue2();
-        if (cls == null || Utils.hasAnyAnnotation(cls::getAnnotation, settings.disableTaggedUnionAnnotations)) {
+        if (cls == null || Utils.hasAnyAnnotation(cls::getAnnotation, settings.disableTaggedUnionAnnotations) || jsonTypeInfo == null) {
+            return false;
+        }
+        // We only support PROPERTY and EXISTING_PROPERTY for tagged unions
+        if(jsonTypeInfo.include() != JsonTypeInfo.As.PROPERTY && jsonTypeInfo.include() != JsonTypeInfo.As.EXISTING_PROPERTY) {
+            return false;
+        }
+        // We don't support NONE, DEDUCTION, or CUSTOM for tagged unions
+        if(
+            jsonTypeInfo.use() == JsonTypeInfo.Id.NONE ||
+            jsonTypeInfo.use() == JsonTypeInfo.Id.DEDUCTION ||
+            jsonTypeInfo.use() == JsonTypeInfo.Id.CUSTOM
+        ) {
             return false;
         }
-        return jsonTypeInfo != null &&
-                (jsonTypeInfo.include() == JsonTypeInfo.As.PROPERTY || jsonTypeInfo.include() == JsonTypeInfo.As.EXISTING_PROPERTY) &&
-                (jsonTypeInfo.use() == JsonTypeInfo.Id.NAME || jsonTypeInfo.use() == JsonTypeInfo.Id.CLASS);
+        return true;
     }
 
     private boolean isDiscriminantPropertySynthetic(JsonTypeInfo jsonTypeInfo) {

typescript-generator-core/src/test/java/cz/habarta/typescript/generator/KotlinTaggedUnionsTest.kt

@@ -0,0 +1,45 @@
+package cz.habarta.typescript.generator
+
+import com.fasterxml.jackson.annotation.JsonTypeInfo
+import org.junit.jupiter.api.Assertions
+import org.junit.jupiter.api.Test
+
+class KotlinTaggedUnionsTest {
+    @JsonTypeInfo(use = JsonTypeInfo.Id.MINIMAL_CLASS)
+    sealed interface MinimalEffort {
+        data class A(
+            val a: String
+        ) : MinimalEffort
+
+        data object B : MinimalEffort
+    }
+
+    @Test
+    fun testMinimalEffortUnions() {
+        val settings = TestUtils.settings()
+        settings.quotes = "'"
+        val output = TypeScriptGenerator(settings)
+            .generateTypeScript(
+                Input.from(
+                    MinimalEffort::class.java,
+                    MinimalEffort.A::class.java,
+                    MinimalEffort.B::class.java
+                )
+            )
+        val expected = """
+        interface MinimalEffort {
+            '@c': 'cz.habarta.typescript.generator.KotlinTaggedUnionsTest${'$'}MinimalEffort${'$'}A' | 'cz.habarta.typescript.generator.KotlinTaggedUnionsTest${'$'}MinimalEffort${'$'}B';
+        }
+
+        interface A extends MinimalEffort {
+            '@c': 'cz.habarta.typescript.generator.KotlinTaggedUnionsTest${'$'}MinimalEffort${'$'}A';
+            a: string;
+        }
+
+        interface B extends MinimalEffort {
+            '@c': 'cz.habarta.typescript.generator.KotlinTaggedUnionsTest${'$'}MinimalEffort${'$'}B';
+        }
+        """.trimIndent()
+        Assertions.assertEquals(expected.trim(), output.trim())
+    }
+}