Error java.lang.IllegalArgumentException: NamedQuery of name: Employee.findAll not found

Question

guys please help me for solve this error, it's been 4 days, this problem hasn't been solved.

this is my Entity Class code :

package mybengkel;

import java.io.Serializable;
import javax.persistence.Basic;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.Table;

/**
 *
 * @author rhmtsaepuloh
 */
@Entity
@Table(name = "employee")
@NamedQueries({
    @NamedQuery(name = "Employee.findAll", query = "SELECT e FROM Employee e"),
    @NamedQuery(name = "Employee.findById", query = "SELECT e FROM Employee e WHERE e.id = :id"),
    @NamedQuery(name = "Employee.findByUsername", query = "SELECT e FROM Employee e WHERE e.username = :username"),
    @NamedQuery(name = "Employee.findByPassword", query = "SELECT e FROM Employee e WHERE e.password = :password")})
public class Employee implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id")
    private Integer id;
    @Basic(optional = false)
    @Column(name = "username")
    private String username;
    @Basic(optional = false)
    @Column(name = "password")
    private String password;

    public Employee() {
    }

    public Employee(Integer id) {
        this.id = id;
    }

    public Employee(Integer id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }

    public Integer getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

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

    public String getPassword() {
        return password;
    }

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

    @Override
    public int hashCode() {
        int hash = 0;
        hash += (id != null ? id.hashCode() : 0);
        return hash;
    }

    @Override
    public boolean equals(Object object) {
        // TODO: Warning - this method won't work in the case the id fields are not set
        if (!(object instanceof Employee)) {
            return false;
        }
        Employee other = (Employee) object;
        if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
            return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return "mybengkel.Employee[ id=" + id + " ]";
    }

}

Persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
  <persistence-unit name="MyBengkelPU" transaction-type="RESOURCE_LOCAL">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    <jar-file>/Users/rhmtsaepuloh/Downloads/mysql-connector-java-8.0.18/mysql-connector-java-8.0.18.jar</jar-file>
    <class>mybengkel.Employee</class>
    <properties>
      <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/oop?serverTimezone=UTC"/>
      <property name="javax.persistence.jdbc.user" value="root"/>
      <property name="javax.persistence.jdbc.driver" value="com.mysql.cj.jdbc.Driver"/>
      <property name="javax.persistence.jdbc.password" value=""/>
      <property name="javax.persistence.schema-generation.database.action" value="create"/>
    </properties>
  </persistence-unit>
</persistence>

and Main class java :

package mybengkel;

import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

/**
 *
 * @author rhmtsaepuloh
 */
public class MyBengkel {

    public static void main(String[] args) {
        EntityManager em;
        EntityManagerFactory emf;
        emf = Persistence.createEntityManagerFactory("MyBengkelPU");
        em = emf.createEntityManager();
        em.getTransaction().begin();

        Employee e = new Employee();
        e.setUsername("haha");
        e.setPassword("hehe");
        em.persist(e);
        em.getTransaction().commit();
    }

}

the problem is when I run the program found error code :

[EL Info]: 2019-11-28 16:07:45.916--ServerSession(347978868)--EclipseLink, version: Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd
[EL Info]: connection: 2019-11-28 16:07:46.813--ServerSession(347978868)--file:/Volumes/Data/Perkuliahan/OOP/NetBeans/MyBengkel/build/classes/_MyBengkelPU login successful
[EL Warning]: metamodel: 2019-11-28 16:07:46.859--The collection of metamodel types is empty. Model classes may not have been found during entity search for Java SE and some Java EE container managed persistence units.  Please verify that your entity classes are referenced in persistence.xml using either <class> elements or a global <exclude-unlisted-classes>false</exclude-unlisted-classes> element
Exception in thread "main" java.lang.IllegalArgumentException: Object: mybengkel.Employee[ id=null ] is not a known entity type.
    at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.registerNewObjectForPersist(UnitOfWorkImpl.java:4228)
    at org.eclipse.persistence.internal.jpa.EntityManagerImpl.persist(EntityManagerImpl.java:496)
    at mybengkel.MyBengkel.main(MyBengkel.java:29)
/Users/rhmtsaepuloh/Library/Caches/NetBeans/11.1/executor-snippets/run.xml:111: The following error occurred while executing this line:
/Users/rhmtsaepuloh/Library/Caches/NetBeans/11.1/executor-snippets/run.xml:68: Java returned: 1
BUILD FAILED (total time: 3 seconds)

I try this on netbeans 11.1 and mysql connector java 8.0.18 Please help me to fix it guys... Thanks before