Can Hadoop ReflectionUtils find private constructors

I need to pass a list of Enum Bucket types between Mapper and Reducer, I have implemented custom BucketArrayWritable according to implementation-of-an-arraywritable-for-a-custom-hadoop-type, and the Bucket Enum has a no-argument constructor, but I always get the error

java.lang.RuntimeException: java.lang.NoSuchMethodException: Bucket.<init>()
    at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:131)
    at org.apache.hadoop.io.WritableFactories.newInstance(WritableFactories.java:58)
    at org.apache.hadoop.io.WritableFactories.newInstance(WritableFactories.java:64)
    at org.apache.hadoop.io.ArrayWritable.readFields(ArrayWritable.java:95)
    at org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.deserialize(WritableSerialization.java:71)
    at org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.deserialize(WritableSerialization.java:42)
    at org.apache.hadoop.mapreduce.task.ReduceContextImpl.nextKeyValue(ReduceContextImpl.java:139)
    at org.apache.hadoop.mapreduce.task.ReduceContextImpl.nextKey(ReduceContextImpl.java:114)
    at org.apache.hadoop.mapreduce.lib.reduce.WrappedReducer$Context.nextKey(WrappedReducer.java:296)
    at org.apache.hadoop.mapreduce.Reducer.run(Reducer.java:163)
    at org.apache.hadoop.mapred.ReduceTask.runNewReducer(ReduceTask.java:610)
    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:444)
    at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:449)
Caused by: java.lang.NoSuchMethodException: com.turn.platform.profile.mapreduce.counting.Bucket.<init>()
    at java.lang.Class.getConstructor0(Class.java:3082)
    at java.lang.Class.getDeclaredConstructor(Class.java:2178)
    at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:125)

Reducer might want to use reflection to init object, but Enum constructors are private by default,

8.9.2 Enum Types
In an enum declaration, a constructor declaration with no access modifiers is private.

I don't know wether it is because Hadoop ReflectionUtils cannot find private constructors

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.function.Predicate;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Writable;


public enum Bucket implements Writable{

    // right bound exclusive
    MAX((count) -> {
        if (count > getValue()) {
            return true;
        }
        return false;
    }, (count, _userId, incre) -> {
        value = count;
        userId = _userId;
    }),
    TOTAL((count) -> {
        return true;
    }),
    BUCKET_0_10((count) -> {
        if (count < 10) {
            return true;
        }
        return false;
    }),
    BUCKET_10_100((count) -> {
        if (count >= 10 && count < 100) {
            return true;
        }
        return false;
    })
    ;

    private static long value = 0;
    private static LongWritable userId = new LongWritable(0);

    private TriConsumer<Long, LongWritable, Long> consumer;
    private Predicate<Long> predicator;

    Bucket() {

    }

    Bucket(Predicate<Long> predicator) {
        this.predicator = predicator;
    }

    Bucket(Predicate<Long> predicator, TriConsumer<Long, LongWritable, Long> consumer) {
        this.consumer = consumer;
        this.predicator = predicator;
    }

    public static long getValue() {
        return value;
    }

    public static void setValue(long newVal) {
        value = newVal;
    }

    public TriConsumer<Long, LongWritable, Long> getConsumer() {
        if (consumer == null) {
            consumer = (count, _userId, incre) -> {
                setValue(getValue() + incre);
                userId = _userId;
            };
        }
        return consumer;
    }

    public Predicate<Long> getPredicator() {
        return predicator;
    }

    @Override
    public void write(DataOutput out) throws IOException {
        out.writeLong(value);
        userId.write(out);
    }

    @Override
    public void readFields(DataInput in) throws IOException {
        value = in.readLong();
        userId.readFields(in);
    }
}