我需要建立一个单向关系，但此错误似乎已映射通过引用未知的目标实体属性（该属性为父级） Caused by: org.hibernate.AnnotationException: mappedBy reference an unknown target entity property

package com.dating.model;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType; 
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;
@Entity
@Table(name="question")
public class PsyQuestions {

    @Id
    @GenericGenerator(name="autoGen" ,strategy="increment")
    @GeneratedValue(generator="autoGen")
    @Column(name="questionid")
    private long psyQuestionId;
    @Column(name="questiontext")
    private String question;

    @OneToMany(fetch = FetchType.LAZY,mappedBy="question")
    private List<PsyOptions> productlist=new ArrayList<PsyOptions>();


    public PsyQuestions() {
        super();
    }

    public List<PsyOptions> getProductlist() {
        return productlist;
    }

    public void setProductlist(List<PsyOptions> productlist) {
        this.productlist = productlist;
    }

    public long getPsyQuestionId() {
        return psyQuestionId;
    }
    public void setPsyQuestionId(long psyQuestionId) {
        this.psyQuestionId = psyQuestionId;
    }
    public String getQuestion() {
        return question;
    }
    public void setQuestion(String question) {
        this.question = question;
    }
}

这个孩子班

package com.dating.model;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

import org.hibernate.annotations.GenericGenerator;

@Entity
@Table(name="option")
public class PsyOptions {

    @Id
    @GenericGenerator(name="autoGen" ,strategy="increment")
    @GeneratedValue(generator="autoGen")
    @Column(name="optionid")
    private long psyOptionId;
    @Column(name="optiontext")
    private String optionText;

    @JoinColumn(name = "questionid")
    @ManyToOne(cascade = CascadeType.ALL,fetch = FetchType.LAZY)
    PsyQuestions psyQuestions;


    public PsyOptions() {
        super();
    }

    public PsyQuestions getPsyQuestions() {
        return psyQuestions;
    }

    public void setPsyQuestions(PsyQuestions psyQuestions) {
        this.psyQuestions = psyQuestions;
    }

    public long getPsyOptionId() {
        return psyOptionId;
    }
    public void setPsyOptionId(long psyOptionId) {
        this.psyOptionId = psyOptionId;
    }
    public String getOptionText() {
        return optionText;
    }
    public void setOptionText(String optionText) {
        this.optionText = optionText;
    }

}