AVRO-4133: Support default enum value in Protobuf to Avro (apache#3367)

* [AVRO-4133] Support default enum value in Protobuf to Avro

* [AVRO-4133] Add unit test for proto schema enum default

* [AVRO-4133] Exclude generated test proto code

---------

Co-authored-by: sivaprasanna <sivaprasanna@sivaprasannas-MacBook-Air.local>

Author: 2 people

lang/java/protobuf/pom.xml

@@ -65,6 +65,10 @@
                       <arg value="--java_out=src/test/java/"/>
                       <arg value="src/test/protobuf/test_multiple_files.proto"/>
                     </exec>
+                    <exec executable="protoc">
+                      <arg value="--java_out=src/test/java/"/>
+                      <arg value="src/test/protobuf/test_proto3.proto"/>
+                    </exec>
                   </target>
                 </configuration>
                 <goals>

lang/java/protobuf/src/main/java/org/apache/avro/protobuf/ProtobufData.java

@@ -301,7 +301,8 @@ private Schema getNonRepeatedSchema(FieldDescriptor f) {
     case SFIXED64:
       return Schema.create(Schema.Type.LONG);
     case ENUM:
-      return getSchema(f.getEnumType());
+      return f.hasDefaultValue() ? getSchema(f.getEnumType(), ((EnumValueDescriptor) f.getDefaultValue()).getName())
+          : getSchema(f.getEnumType());
     case MESSAGE:
       result = getSchema(f.getMessageType());
       if (f.isOptional())
@@ -315,11 +316,22 @@ private Schema getNonRepeatedSchema(FieldDescriptor f) {
   }
 
   public Schema getSchema(EnumDescriptor d) {
+    List<String> symbols = getEnumSymbols(d);
+    String enumDefault = symbols.isEmpty() ? null : symbols.get(0);
+    return Schema.createEnum(d.getName(), null, getNamespace(d.getFile(), d.getContainingType()), symbols, enumDefault);
+  }
+
+  public Schema getSchema(EnumDescriptor d, String enumDefault) {
+    List<String> symbols = getEnumSymbols(d);
+    return Schema.createEnum(d.getName(), null, getNamespace(d.getFile(), d.getContainingType()), symbols, enumDefault);
+  }
+
+  private List<String> getEnumSymbols(EnumDescriptor d) {
     List<String> symbols = new ArrayList<>(d.getValues().size());
     for (EnumValueDescriptor e : d.getValues()) {
       symbols.add(e.getName());
     }
-    return Schema.createEnum(d.getName(), null, getNamespace(d.getFile(), d.getContainingType()), symbols);
+    return symbols;
   }
 
   private static final JsonFactory FACTORY = new JsonFactory();

lang/java/protobuf/src/test/java/org/apache/avro/protobuf/TestProtobuf.java

@@ -24,6 +24,7 @@
 import org.apache.avro.io.DecoderFactory;
 import org.apache.avro.io.Encoder;
 import org.apache.avro.io.EncoderFactory;
+import org.apache.avro.protobuf.noopt.TestProto3;
 import org.apache.avro.specific.SpecificData;
 import org.apache.commons.compress.utils.Lists;
 import org.junit.jupiter.api.Test;
@@ -146,4 +147,17 @@ void getNonRepeatedSchemaWithLogicalType() throws Exception {
     Schema s2 = instance2.getSchema(com.google.protobuf.Timestamp.class);
     assertEquals(conversion.getRecommendedSchema(), s2);
   }
+
+  @Test
+  void enumDefault() {
+    Schema fooSchema = ProtobufData.get().getSchema(Foo.class);
+    assertEquals("Z", fooSchema.getField("enum").schema().getEnumDefault());
+
+    Schema nSchema = ProtobufData.get().getSchema(N.class);
+    assertEquals("A", nSchema.getEnumDefault());
+
+    Schema proto3Schema = ProtobufData.get().getSchema(TestProto3.User.class);
+    assertEquals("STATUS_UNKNOWN", proto3Schema.getField("status").defaultVal());
+    assertEquals("STATUS_UNKNOWN", proto3Schema.getField("status").schema().getEnumDefault());
+  }
 }