How to add a Checkbox property for Spring form

I've been building a Spring MVC application that uses SpringDataJPA and hibernate, and leverages MySQL. From some point on I am getting an NumberFormatException for a specific form on my main web-page (named 'main'), which I wasn't able to get rid of. Can you show me where my code went wrong?

Main.JSP

            <spring:bind path="sid">
                <tr>
                    <label for="sid">Choose Preferred Scholar:</label>
                    <c:forEach items="${scholarList}" var="scholar">
                        <td><form:checkbox path="sid" id="${scholar.id}" label="${scholar.fname}" value="${scholar.id}" /></td>
                    </c:forEach>
                </tr>
            </spring:bind>

Stack Trace

org.apache.catalina.core.ApplicationDispatcher invoke
SEVERE: Servlet.service() for servlet [jsp] threw exception
java.lang.NumberFormatException: For input string: "id"
    at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.base/java.lang.Integer.parseInt(Integer.java:652)
    at java.base/java.lang.Integer.parseInt(Integer.java:770)
    at javax.el.ArrayELResolver.coerce(ArrayELResolver.java:144)
    at javax.el.ArrayELResolver.getValue(ArrayELResolver.java:61)
    at org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:113)
    at org.apache.el.parser.AstValue.getValue(AstValue.java:169)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:190)
    at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:701)
    at org.apache.jsp.WEB_002dINF.views.main_jsp._jspx_meth_form_005fcheckbox_005f0(main_jsp.java:1214)
    at org.apache.jsp.WEB_002dINF.views.main_jsp._jspx_meth_c_005fforEach_005f2(main_jsp.java:1174)
    at org.apache.jsp.WEB_002dINF.views.main_jsp._jspService(main_jsp.java:350)

Controller

@RequestMapping(value = { "/main" }, method = RequestMethod.GET)
    public String welcome(Model model) {
        model.addAttribute("addProject", new Projects());
        model.addAttribute("projectList", projectService.getAllProjects());
        model.addAttribute("availableProjectList", projectService.getAvailableProjects());
        model.addAttribute("scholarList", userService.getScholars());
        model.addAttribute("technologiesList", techService.getAllTechnologies());

        return "main";
    }

Service

@SuppressWarnings("unchecked")
    @Override
    @Transactional
    public List<User> getScholars() {
        return entityManager.createNativeQuery("select * from User").getResultList();
    }

User Entity

package com.ajwt.entities;
// Generated 17 באפר׳ 2019, 2:45:49 by Hibernate Tools 4.3.5.Final

import java.util.Date;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import static javax.persistence.GenerationType.IDENTITY;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.OneToOne;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

/**
 * User generated by hbm2java
 */
@Entity
@Table(name = "user", catalog = "ajwt")
public class User implements java.io.Serializable {

    private Integer id;
    private String username;
    private String email;
    private String password;
    private String passwordConfirm;
    public String getPasswordConfirm() {
        return passwordConfirm;
    }

    public void setPasswordConfirm(String confirmPassword) {
        this.passwordConfirm = confirmPassword;
    }

    private Date createTime;
    private String fname;
    private String lname;
    private Set<Roles> roleses = new HashSet<Roles>(0);
    private Set<Projects> projectses = new HashSet<Projects>(0);
    private Projects projects;

    public User() {
    }

    public User(String username, String email, String password, String fname, String lname) {
        this.username = username;
        this.email = email;
        this.password = password;
        this.fname = fname;
        this.lname = lname;
    }

    public User(String username, String email, String password, Date createTime, String fname, String lname,
            Set<Roles> roleses, Set<Projects> projectses, Projects projects) {
        this.username = username;
        this.email = email;
        this.password = password;
        this.createTime = createTime;
        this.fname = fname;
        this.lname = lname;
        this.roleses = roleses;
        this.projectses = projectses;
        this.projects = projects;
    }

    @Id
    @GeneratedValue(strategy = IDENTITY)

    @Column(name = "id", unique = true, nullable = false)
    public Integer getId() {
        return this.id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    @Column(name = "username", nullable = false, length = 16)
    public String getUsername() {
        return this.username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    @Column(name = "email", nullable = false)
    public String getEmail() {
        return this.email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Column(name = "password", nullable = false)
    public String getPassword() {
        return this.password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "create_time", length = 26)
    public Date getCreateTime() {
        return this.createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }

    @Column(name = "fname", nullable = false, length = 45)
    public String getFname() {
        return this.fname;
    }

    public void setFname(String fname) {
        this.fname = fname;
    }

    @Column(name = "lname", nullable = false, length = 45)
    public String getLname() {
        return this.lname;
    }

    public void setLname(String lname) {
        this.lname = lname;
    }

    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable(name = "user_role", catalog = "ajwt", joinColumns = {
            @JoinColumn(name = "uid", nullable = false, updatable = false) }, inverseJoinColumns = {
                    @JoinColumn(name = "rid", nullable = false, updatable = false) })
    public Set<Roles> getRoleses() {
        return this.roleses;
    }

    public void setRoleses(Set<Roles> roleses) {
        this.roleses = roleses;
    }

    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable(name = "participating_students", catalog = "ajwt", joinColumns = {
            @JoinColumn(name = "usid", nullable = false, updatable = false) }, inverseJoinColumns = {
                    @JoinColumn(name = "pid", nullable = false, updatable = false) })
    public Set<Projects> getProjectses() {
        return this.projectses;
    }

    public void setProjectses(Set<Projects> projectses) {
        this.projectses = projectses;
    }

    @OneToOne(fetch = FetchType.LAZY, mappedBy = "user")
    public Projects getProjects() {
        return this.projects;
    }

    public void setProjects(Projects projects) {
        this.projects = projects;
    }

}