GH-2956: Use avro SchemaBuilder API to convert record (#2957)

The avro schema builder API is cleaned and more stable. It decreases
chance of using newly introduced avro API in case user run with legacy
avro version

As OPTIONAL converted fields sets null as default, increase consistency
by using [] as default for REPEATED converted fields.

Author: RustedBones

parquet-avro/src/main/java/org/apache/parquet/avro/AvroSchemaConverter.java

@@ -20,7 +20,6 @@
 
 import static java.util.Optional.empty;
 import static java.util.Optional.of;
-import static org.apache.avro.JsonProperties.NULL_VALUE;
 import static org.apache.parquet.avro.AvroReadSupport.READ_INT96_AS_FIXED;
 import static org.apache.parquet.avro.AvroReadSupport.READ_INT96_AS_FIXED_DEFAULT;
 import static org.apache.parquet.avro.AvroWriteSupport.WRITE_FIXED_AS_INT96;
@@ -58,6 +57,7 @@
 import org.apache.avro.LogicalType;
 import org.apache.avro.LogicalTypes;
 import org.apache.avro.Schema;
+import org.apache.avro.SchemaBuilder;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.parquet.conf.HadoopParquetConfiguration;
 import org.apache.parquet.conf.ParquetConfiguration;
@@ -296,21 +296,24 @@ Schema convert(GroupType parquetSchema) {
   }
 
   private Schema convertFields(String name, List<Type> parquetFields, Map<String, Integer> names) {
-    String ns = namespace(name, names);
-    List<Schema.Field> fields = new ArrayList<Schema.Field>();
+    SchemaBuilder.FieldAssembler<Schema> builder =
+        SchemaBuilder.builder(namespace(name, names)).record(name).fields();
     for (Type parquetType : parquetFields) {
       Schema fieldSchema = convertField(parquetType, names);
       if (parquetType.isRepetition(REPEATED)) { // If a repeated field is ungrouped, treat as REQUIRED per spec
-        fields.add(new Schema.Field(parquetType.getName(), Schema.createArray(fieldSchema)));
+        builder.name(parquetType.getName())
+            .type()
+            .array()
+            .items()
+            .type(fieldSchema)
+            .arrayDefault(new ArrayList<>());
       } else if (parquetType.isRepetition(Type.Repetition.OPTIONAL)) {
-        fields.add(new Schema.Field(parquetType.getName(), optional(fieldSchema), null, NULL_VALUE));
+        builder.name(parquetType.getName()).type().optional().type(fieldSchema);
       } else { // REQUIRED
-        fields.add(new Schema.Field(parquetType.getName(), fieldSchema, null, (Object) null));
+        builder.name(parquetType.getName()).type(fieldSchema).noDefault();
       }
     }
-    Schema schema = Schema.createRecord(name, null, ns, false);
-    schema.setFields(fields);
-    return schema;
+    return builder.endRecord();
   }
 
   private Schema convertField(final Type parquetType, Map<String, Integer> names) {

parquet-avro/src/test/java/org/apache/parquet/avro/TestAvroSchemaConverter.java

@@ -72,43 +72,43 @@ public static void setupConf() {
     NEW_BEHAVIOR.setBoolean("parquet.avro.write-old-list-structure", false);
   }
 
-  public static final String ALL_PARQUET_SCHEMA =
-      "message org.apache.parquet.avro.myrecord {\n" + "  required boolean myboolean;\n"
-          + "  required int32 myint;\n"
-          + "  required int64 mylong;\n"
-          + "  required float myfloat;\n"
-          + "  required double mydouble;\n"
-          + "  required binary mybytes;\n"
-          + "  required binary mystring (UTF8);\n"
-          + "  required group mynestedrecord {\n"
-          + "    required int32 mynestedint;\n"
-          + "  }\n"
-          + "  required binary myenum (ENUM);\n"
-          + "  required group myarray (LIST) {\n"
-          + "    repeated int32 array;\n"
-          + "  }\n"
-          + "  optional group myoptionalarray (LIST) {\n"
-          + "    repeated int32 array;\n"
-          + "  }\n"
-          + "  required group myarrayofoptional (LIST) {\n"
-          + "    repeated group list {\n"
-          + "      optional int32 element;\n"
-          + "    }\n"
-          + "  }\n"
-          + "  required group myrecordarray (LIST) {\n"
-          + "    repeated group array {\n"
-          + "      required int32 a;\n"
-          + "      required int32 b;\n"
-          + "    }\n"
-          + "  }\n"
-          + "  required group mymap (MAP) {\n"
-          + "    repeated group map (MAP_KEY_VALUE) {\n"
-          + "      required binary key (UTF8);\n"
-          + "      required int32 value;\n"
-          + "    }\n"
-          + "  }\n"
-          + "  required fixed_len_byte_array(1) myfixed;\n"
-          + "}\n";
+  public static final String ALL_PARQUET_SCHEMA = "message org.apache.parquet.avro.myrecord {\n"
+      + "  required boolean myboolean;\n"
+      + "  required int32 myint;\n"
+      + "  required int64 mylong;\n"
+      + "  required float myfloat;\n"
+      + "  required double mydouble;\n"
+      + "  required binary mybytes;\n"
+      + "  required binary mystring (UTF8);\n"
+      + "  required group mynestedrecord {\n"
+      + "    required int32 mynestedint;\n"
+      + "  }\n"
+      + "  required binary myenum (ENUM);\n"
+      + "  required group myarray (LIST) {\n"
+      + "    repeated int32 array;\n"
+      + "  }\n"
+      + "  optional group myoptionalarray (LIST) {\n"
+      + "    repeated int32 array;\n"
+      + "  }\n"
+      + "  required group myarrayofoptional (LIST) {\n"
+      + "    repeated group list {\n"
+      + "      optional int32 element;\n"
+      + "    }\n"
+      + "  }\n"
+      + "  required group myrecordarray (LIST) {\n"
+      + "    repeated group array {\n"
+      + "      required int32 a;\n"
+      + "      required int32 b;\n"
+      + "    }\n"
+      + "  }\n"
+      + "  required group mymap (MAP) {\n"
+      + "    repeated group map (MAP_KEY_VALUE) {\n"
+      + "      required binary key (UTF8);\n"
+      + "      required int32 value;\n"
+      + "    }\n"
+      + "  }\n"
+      + "  required fixed_len_byte_array(1) myfixed;\n"
+      + "}\n";
 
   private void testAvroToParquetConversion(Schema avroSchema, String schemaString) throws Exception {
     testAvroToParquetConversion(new Configuration(false), avroSchema, schemaString);
@@ -432,7 +432,8 @@ public void testConvertUngroupedRepeatedField() throws Exception {
                 + "  \"name\": \"SchemaWithRepeatedField\","
                 + "  \"fields\": [{"
                 + "    \"name\": \"repeatedField\","
-                + "    \"type\": {\"type\": \"array\",\"items\": \"int\"}"
+                + "    \"type\": {\"type\": \"array\",\"items\": \"int\"},"
+                + "    \"default\": []"
                 + "  }]"
                 + "}"),
         "message SchemaWithRepeatedField { repeated int32 repeatedField; }");