title: Spring Boot one to many unidirectional
body: <p>I have the entity Project and entity Cluster.
  A Project can have multiple Clusters.
  I don't want a third table to save this relationship. Just the Project ID saved to the Cluster.</p>
  
  <p>This is my project Entity:</p>
  
  <pre><code>@Entity
  @Table(name = "Project")
  public class Project {
  
      @Id
      @GeneratedValue(strategy = GenerationType.AUTO)
      private Integer id;
  
      private String projectName;
  
      @OneToMany
      @JoinTable(name = "cluster")
      private Set&lt;Cluster&gt; clusters;
  }
  </code></pre>
  
  <p>This is my Cluster entity</p>
  
  <pre><code>@Entity
  @Table(name = "Cluster")
  public class Cluster {
  
      @Id
      @GeneratedValue(strategy = GenerationType.AUTO)
      private Integer id;
  
      private String team;
  
      private String concept;
  }   
  </code></pre>
  
  <p>This gives me the error: must have same number of columns as the referenced primary key .</p>
  
  <p>How could I fix this? I don't see how to fix this.</p>