an RxRelay BehaviorRelay wrapper that only allows a value to be added once

SingleValueRelay.java

package com.jakewharton.rxrelay2;

import io.reactivex.Observer;

public class SingleValueRelay<T> extends Relay<T> {
    private final BehaviorRelay<T> behaviorRelay = BehaviorRelay.create();


    public SingleValueRelay() {}

    @Override
    public void accept(T value) {
        if (!behaviorRelay.hasValue()) {
            behaviorRelay.accept(value);
        }
    }

    @Override
    public boolean hasObservers() {
        return behaviorRelay.hasObservers();
    }

    @Override
    protected void subscribeActual(Observer<? super T> observer) {
        behaviorRelay.subscribeActual(observer);
    }

    public boolean hasValue() {
        return behaviorRelay.hasValue();
    }

    public T getValue() {
        return behaviorRelay.getValue();
    }
}