[Avro] @AvroNamespace annotation to override Avro type namespace (#324)

New annotation @AvroNamespace to override Avro schema field namespace. Current namespace value is Java package name. This annotation allows to override its name.

Author: MichalFoksa

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/annotations/AvroNamespace.java

@@ -0,0 +1,16 @@
+package com.fasterxml.jackson.dataformat.avro.annotations;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation allows to override default Avro type namespace value.
+ * Default value is Java package name.
+ */
+@Target({ElementType.TYPE, ElementType.ANNOTATION_TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface AvroNamespace {
+    String value();
+}

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

@@ -1,6 +1,5 @@
 package com.fasterxml.jackson.dataformat.avro.schema;
 
-import com.fasterxml.jackson.databind.util.LRUMap;
 import java.io.File;
 import java.math.BigDecimal;
 import java.math.BigInteger;
@@ -23,6 +22,8 @@
 import com.fasterxml.jackson.databind.json.JsonMapper;
 import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonFormatTypes;
 import com.fasterxml.jackson.databind.util.ClassUtil;
+import com.fasterxml.jackson.databind.util.LRUMap;
+import com.fasterxml.jackson.dataformat.avro.annotations.AvroNamespace;
 
 public abstract class AvroSchemaHelper
 {
@@ -97,8 +98,9 @@ public static boolean isStringable(AnnotatedClass type) {
         return false;
     }
 
-    protected static String getNamespace(JavaType type) {
-        return getNamespace(type.getRawClass());
+    protected static String getNamespace(BeanDescription bean) {
+        AvroNamespace ann = bean.getClassInfo().getAnnotation(AvroNamespace.class);
+        return ann != null ? ann.value() : getNamespace(bean.getType().getRawClass());
     }
 
     protected static String getNamespace(Class<?> cls) {
@@ -244,7 +246,7 @@ public static Schema initializeRecordSchema(BeanDescription bean) {
         return addAlias(Schema.createRecord(
             getName(bean.getType()),
             bean.findClassDescription(),
-            getNamespace(bean.getType()),
+            getNamespace(bean),
             bean.getType().isTypeOrSubTypeOf(Throwable.class)
         ), bean);
     }
@@ -268,7 +270,7 @@ public static Schema createEnumSchema(BeanDescription bean, List<String> values)
         return addAlias(Schema.createEnum(
             getName(bean.getType()),
             bean.findClassDescription(),
-            getNamespace(bean.getType()), values
+            getNamespace(bean), values
         ), bean);
     }
 

avro/src/test/java/com/fasterxml/jackson/dataformat/avro/annotations/AvroNamespaceTest.java

@@ -0,0 +1,85 @@
+package com.fasterxml.jackson.dataformat.avro.annotations;
+
+import com.fasterxml.jackson.databind.JsonMappingException;
+import com.fasterxml.jackson.dataformat.avro.AvroMapper;
+import com.fasterxml.jackson.dataformat.avro.schema.AvroSchemaGenerator;
+import org.apache.avro.Schema;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class AvroNamespaceTest {
+
+    static class ClassWithoutAvroNamespaceAnnotation {
+    }
+
+    @AvroNamespace("ClassWithAvroNamespaceAnnotation.namespace")
+    static class ClassWithAvroNamespaceAnnotation {
+    }
+
+    enum EnumWithoutAvroNamespaceAnnotation {FOO, BAR;}
+
+    @AvroNamespace("EnumWithAvroNamespaceAnnotation.namespace")
+    enum EnumWithAvroNamespaceAnnotation {FOO, BAR;}
+
+    @Test
+    public void class_without_AvroNamespace_test() throws JsonMappingException {
+        // GIVEN
+        AvroMapper mapper = new AvroMapper();
+        AvroSchemaGenerator gen = new AvroSchemaGenerator();
+
+        // WHEN
+        mapper.acceptJsonFormatVisitor(ClassWithoutAvroNamespaceAnnotation.class, gen);
+        Schema actualSchema = gen.getGeneratedSchema().getAvroSchema();
+
+        // THEN
+        assertThat(actualSchema.getNamespace())
+                .isEqualTo("com.fasterxml.jackson.dataformat.avro.annotations.AvroNamespaceTest$");
+    }
+
+    @Test
+    public void class_with_AvroNamespace_test() throws JsonMappingException {
+        // GIVEN
+        AvroMapper mapper = new AvroMapper();
+        AvroSchemaGenerator gen = new AvroSchemaGenerator();
+
+        // WHEN
+        mapper.acceptJsonFormatVisitor(ClassWithAvroNamespaceAnnotation.class, gen);
+        Schema actualSchema = gen.getGeneratedSchema().getAvroSchema();
+
+        // THEN
+        assertThat(actualSchema.getNamespace())
+                .isEqualTo("ClassWithAvroNamespaceAnnotation.namespace");
+    }
+
+    @Test
+    public void enum_without_AvroNamespace_test() throws JsonMappingException {
+        // GIVEN
+        AvroMapper mapper = new AvroMapper();
+        AvroSchemaGenerator gen = new AvroSchemaGenerator();
+
+        // WHEN
+        mapper.acceptJsonFormatVisitor(EnumWithoutAvroNamespaceAnnotation.class, gen);
+        Schema actualSchema = gen.getGeneratedSchema().getAvroSchema();
+
+        // THEN
+        assertThat(actualSchema.getNamespace())
+                .isEqualTo("com.fasterxml.jackson.dataformat.avro.annotations.AvroNamespaceTest$");
+    }
+
+    @Test
+    public void enum_with_AvroNamespace_test() throws JsonMappingException {
+        // GIVEN
+        AvroMapper mapper = new AvroMapper();
+        AvroSchemaGenerator gen = new AvroSchemaGenerator();
+
+        // WHEN
+        mapper.acceptJsonFormatVisitor(EnumWithAvroNamespaceAnnotation.class, gen);
+        Schema actualSchema = gen.getGeneratedSchema().getAvroSchema();
+
+        // THEN
+        assertThat(actualSchema.getNamespace())
+                .isEqualTo("EnumWithAvroNamespaceAnnotation.namespace");
+    }
+
+}