Java – error: importing com google. appengine. api. Datastore failed to parse JPA gae GWT

Error in development mode

[ERROR] [cbd] - Line 15: The import com.google.appengine.api.datastore cannot be resolved

User. java

@Entity
public class User implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @Column(name="id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Key id;

    private String googleID;

    private String firstName;

    private String lastName;

    private String password;

    private String gender;

    private String email;


    @OneToOne(cascade=CascadeType.ALL)
    @JoinColumn(name="key")
    private AuthenticationToken token= AuthenticationToken();
    ......}

AuthenticationToken. java

public class AuthenticationToken implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    @Id
    @Column(name="key")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Key key;

    private String email;

    private String token;

    private Date obtained;

    private Date activity;
    .....}

persistence. In XML

<?xml version="1.0" encoding="UTF-8" ?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
        http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0">

    <persistence-unit name="transactions-optional">


        <provider>org.datanucleus.api.jpa.PersistenceProviderImpl</provider>

        <class>com.cbd.shared.entities.User</class>

    <class>com.cbd.shared.entities.AuthenticationToken</class>

    <exclude-unlisted-classes>true</exclude-unlisted-classes>

        <properties>
            <property name="datanucleus.NontransactionalRead" value="true"/>
            <property name="datanucleus.NontransactionalWrite" value="true"/>
            <property name="datanucleus.ConnectionURL" value="appengine"/>
        </properties>
    </persistence-unit>
</persistence>

I'm using GWT to try to move the entity to the server instead of sharing the package, but the same error

Solution

Errors found The datanucleus plug-in was not added to eclipse, so some JPA libraries were not explicitly defined in the project runtime