JSON syntax error in Hibernate model

I have 2 model classes: Project and Task. They have a one-to-many relationship; that is, one Project can have many Tasks and one Task has only one Project.

Project class:

@Entity
@Table(name = "project")
public class Project implements Serializable{
   private int  project_id;
   private int manager_id;
   private String name;
   private String description;
   private  Set<Task> Projects = new HashSet<Task>();

   @Id
   @Column(name = "project_id")
   public int getProject_id() {
       return project_id;
   }

   @Column(name = "manager_id")
   public int getManager_id() {
       return manager_id;
   }

   @Column(name = "name")
   public String getName() {
       return name;
   }

   @Column(name = "description")
   public String getDescription() {
       return description;
   }

   public void setProject_id(int project_id) {
       this.project_id = project_id;
   }

   public void setManager_id(int manager_id) {
       this.manager_id = manager_id;
   }

   public void setName(String name) {
       this.name = name;
   }

   public void setDescription(String description) {
       this.description = description;
   }

   @OneToMany(fetch = FetchType.EAGER, mappedBy = "project", cascade = CascadeType.ALL)
   public Set<Task> getProjects() {
       return Projects;
   }

   public void setProjects(Set<Task> Projects) {
       this.Projects = Projects;
   }
}

Task class:

@Entity
@Table(name = "task")
public class Task implements Serializable {
    private int task_id;
    private Project project;
    private int developer_id; 
    private String date ;       
    private String hours; 
    private String description; 
    private String overtime;

    @Id
    @Column(name = "task_id")
    public int getTask_id() {
        return task_id;
    }

    @Column(name = "developer_id")
    public int getDeveloper_id() {
        return developer_id;
    }

    @Column(name = "date")
    public String getDate() {
        return date;
    }

    @Column(name = "hours")
    public String getHours() {
        return hours;
    }

    @Column(name = "description")
    public String getDescription() {
        return description;
    }

    @Column(name = "overtime")
    public String getOvertime() {
        return overtime;
    }

    public void setTask_id(int task_id) {
        this.task_id = task_id;
    }

    public void setDeveloper_id(int developer_id) {
        this.developer_id = developer_id;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public void setHours(String hours) {
        this.hours = hours;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public void setOvertime(String overtime) {
        this.overtime = overtime;
    }

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "project_id")
    public Project getProject() {
        return project;
    }

    public void setProject(Project project) {
        this.project = project;
    }
}

I have used a one-to-many relationship in Hibernate to get a JSON output, but I get the following error:

SyntaxError: JSON.parse: expected ':' after property name in object at line 1 column 81390 of the JSON data

Also there is a huge data set in raw data.