Fix build after AVRO-3230

This explicitly enables and disables fastreader to ensure both are
tested.

Author: opwvhk

lang/java/avro/src/test/java/org/apache/avro/TestReadingWritingDataInEvolvedSchemas.java

@@ -438,7 +438,9 @@ private Record decodeGenericBlob(Schema expectedSchema, Schema schemaOfBlob, byt
     if (blob == null) {
       return null;
     }
-    GenericDatumReader<Record> reader = new GenericDatumReader<>();
+    GenericData data = new GenericData();
+    data.setFastReaderEnabled(true);
+    GenericDatumReader<Record> reader = new GenericDatumReader<>(null, null, data);
     reader.setExpected(expectedSchema);
     reader.setSchema(schemaOfBlob);
     Decoder decoder = encoderType == EncoderType.BINARY ? DecoderFactory.get().binaryDecoder(blob, null)

lang/java/avro/src/test/java/org/apache/avro/TestSchemaCompatibilityEnumDefaults.java

@@ -27,6 +27,8 @@
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.io.ByteArrayOutputStream;
+import java.util.concurrent.Callable;
+
 import org.apache.avro.generic.GenericData;
 import org.apache.avro.generic.GenericDatumReader;
 import org.apache.avro.generic.GenericDatumWriter;
@@ -127,8 +129,9 @@ private GenericRecord serializeWithWriterThenDeserializeWithReader(Schema writer
     byte[] bytes = baos.toByteArray();
     Decoder decoder = DecoderFactory.get().resolvingDecoder(writerSchema, readerSchema,
         DecoderFactory.get().binaryDecoder(bytes, null));
-    DatumReader<Object> datumReader = new GenericDatumReader<>(readerSchema);
+    GenericData data = new GenericData();
+    data.setFastReaderEnabled(false);
+    DatumReader<Object> datumReader = new GenericDatumReader<>(readerSchema, readerSchema, data);
     return (GenericRecord) datumReader.read(null, decoder);
   }
-
 }

lang/java/avro/src/test/java/org/apache/avro/TestUnionError.java

@@ -23,6 +23,7 @@
 import org.apache.avro.generic.GenericRecord;
 import org.apache.avro.io.BinaryDecoder;
 import org.apache.avro.io.BinaryEncoder;
+import org.apache.avro.io.DatumReader;
 import org.apache.avro.io.DecoderFactory;
 import org.apache.avro.io.EncoderFactory;
 
@@ -77,7 +78,9 @@ void unionErrorMessage() throws IOException {
     InputStream ins = new ByteArrayInputStream(outs.toByteArray());
     BinaryDecoder decoder = DecoderFactory.get().binaryDecoder(ins, null);
 
-    GenericDatumReader<GenericRecord> datumReader = new GenericDatumReader<>(writerSchema, readerSchema);
+    GenericData data = new GenericData();
+    data.setFastReaderEnabled(false);
+    GenericDatumReader<GenericRecord> datumReader = new GenericDatumReader<>(writerSchema, readerSchema, data);
     AvroTypeException avroException = assertThrows(AvroTypeException.class, () -> datumReader.read(null, decoder));
     assertEquals("Field \"c\" content mismatch: Found B, expecting union[A, float]", avroException.getMessage());
   }