Support enum avro serialization with default value

Author: Sonic-Rage

avro/pom.xml

@@ -47,7 +47,7 @@ abstractions.
     <dependency>
       <groupId>org.apache.avro</groupId>
       <artifactId>avro</artifactId>
-      <version>1.8.2</version>
+      <version>1.9.2</version>
     </dependency>
 
     <!-- and for testing we need logback -->

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/schema/AvroSchemaHelper.java

@@ -19,6 +19,7 @@
 import com.fasterxml.jackson.databind.*;
 import com.fasterxml.jackson.databind.introspect.AnnotatedClass;
 import com.fasterxml.jackson.databind.introspect.AnnotatedConstructor;
+import com.fasterxml.jackson.databind.introspect.JacksonAnnotationIntrospector;
 import com.fasterxml.jackson.databind.json.JsonMapper;
 import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonFormatTypes;
 import com.fasterxml.jackson.databind.util.ClassUtil;
@@ -71,6 +72,14 @@ public abstract class AvroSchemaHelper
             String.class
     ));
 
+    /**
+     * 
+     * Jackson annotation introspector for verifying enum default annotation for Avro Schema generation
+     * 
+     * @since 2.16
+     */
+    private static final JacksonAnnotationIntrospector JACKSON_ANNOTATION_INTROSPECTOR = new JacksonAnnotationIntrospector();
+
     /**
      * Checks if a given type is "Stringable", that is one of the default
      * {@code STRINGABLE_CLASSES}, is an {@code Enum},
@@ -269,10 +278,11 @@ public static Schema parseJsonSchema(String json) {
      */
     public static Schema createEnumSchema(BeanDescription bean, List<String> values) {
         final JavaType enumType = bean.getType();
+        Enum<?> defaultEnumValue = JACKSON_ANNOTATION_INTROSPECTOR.findDefaultEnumValue((Class<Enum<?>>)(Class<?>) enumType.getRawClass());
         return addAlias(Schema.createEnum(
             getName(enumType),
             bean.findClassDescription(),
-            getNamespace(enumType, bean.getClassInfo()), values
+            getNamespace(enumType, bean.getClassInfo()), values, defaultEnumValue != null ? defaultEnumValue.toString() : null
         ), bean);
     }
 

avro/src/test/java/com/fasterxml/jackson/dataformat/avro/AvroTestBase.java

@@ -9,6 +9,8 @@
 import junit.framework.TestCase;
 
 import com.fasterxml.jackson.annotation.JsonPropertyOrder;
+import com.fasterxml.jackson.annotation.JsonEnumDefaultValue;
+import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.core.JsonToken;
 import com.fasterxml.jackson.databind.ObjectMapper;
@@ -249,6 +251,19 @@ public Image(String uri, String title, int w, int h, Size s)
 
     public enum Size { SMALL, LARGE; }
 
+    public enum ABC { 
+		A, 
+		B, 
+		@JsonEnumDefaultValue
+		C; 
+	}
+
+    public static class ABCDefaultClass {
+        public String name;
+        @JsonProperty(required = true)
+        public ABC abc;
+    }
+
     /*
     /**********************************************************
     /* Recycling for commonly needed helper objects

avro/src/test/java/com/fasterxml/jackson/dataformat/avro/schema/SchemaGenerationTest.java

@@ -11,6 +11,7 @@
 import com.fasterxml.jackson.dataformat.avro.*;
 
 import org.apache.avro.Schema;
+import org.apache.avro.Schema.Type;
 
 public class SchemaGenerationTest extends AvroTestBase
 {
@@ -169,4 +170,38 @@ public void testSchemaForUntypedMap() throws Exception
             verifyException(e, "Maps with non-stringable keys are not supported (yet?)");
         }
     }
+
+    // Issue 388 Default value for enums with class
+    public void testClassEnumWithDefault() throws Exception
+    {
+        AvroSchemaGenerator gen = new AvroSchemaGenerator();
+
+        MAPPER.acceptJsonFormatVisitor(ABCDefaultClass.class, gen);
+        AvroSchema schema = gen.getGeneratedSchema();
+        assertNotNull(schema);
+
+        String json = schema.getAvroSchema().toString(true);
+        assertNotNull(json);
+
+
+        // And read it back too just for fun
+        AvroSchema s2 = MAPPER.schemaFrom(json);
+        assertNotNull(s2);
+
+        Schema avroSchema = s2.getAvroSchema();
+
+        // String name, int value
+        assertEquals(Type.RECORD, avroSchema.getType());
+        Schema.Field f = avroSchema.getField("abc");
+        assertNotNull(f);
+        assertEquals("abc", f.name());
+
+        assertEquals(Type.ENUM, f.schema().getType());
+        assertEquals(ABC.C.toString(), f.schema().getEnumDefault());
+        assertEquals(Stream.of(ABC.values())
+                               .map(ABC::name)
+                               .collect(Collectors.toList()), f.schema().getEnumSymbols());
+
+
+    }
 }