org.hibernate.MappingException: Could not determine type for: , at table: Sentence, for columns:

Question

I get this error on execution: org.hibernate.MappingException: Could not determine type for: transcriptParsing.structures.Participant, at table: Sentence, for columns: [org.hibernate.mapping.Column(participant)]

I have the following class structures

@Entity
@Table(name="Sentence")
public class Sentence {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int id;
    public String wholeSentence;

    @ManyToOne
    @JoinColumn(name = "participant_id", foreignKey = @ForeignKey(name = "participant_ID_FK"))
    public Participant participant;
    public Category sentenceType;
    public enum Category {
        Question,
        Answer
    }


@Entity
@Table(name="Participant")
public class Participant {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public int id;
    @Column
    public String name;
    @Column
    public Category category;
    public enum Category {
        Management,
        Analyst
    }

What could be wrong here? Really appreciate the help, Thanks!