Referencing join column in JPQL

With the query Select c from Card c join User u on c.userId=u.userId where u.username=':u', I am trying to grab a list of Cards for the User based on the username available in User the table. However, I am running into the antlr.SemanticException: could not resolve property: userId of: com.abc.SheridanSportsWAR.entity.Card exception when I run it. How do I reference the UserId column in my Card entity?

Card.java

@Entity
public class Card {
	
	@Id
	@Column(name="CardId")
	@GeneratedValue(strategy = GenerationType.AUTO)
	private Integer cardId;
	
	@Column(name="CardNumber")
	private String cardNumber;
	
	@Column(name="CardType")
	private String cardType;
	
	@Column(name="ExpiryMonth")
	private String expiryMonth;
	
	@Column(name="ExpiryYear")
	private String expiryYear;
	
	@Column(name="CardHolder")
	private String cardHolder;

	@ManyToOne(cascade = {CascadeType.MERGE, CascadeType.DETACH, CascadeType.PERSIST, CascadeType.REFRESH})
	@JoinColumn(name = "UserId")
	private User userJ;
	
	@OneToMany(mappedBy = "cardJ")
	private List<Purchase> purchases;

User.java

@Entity
public class User {
	
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name="UserId")
	private Integer userId;
	
	@Column(name="FirstName")
	private String firstName;
	
	@Column(name="LastName")
	private String lastName;
	
	@Column(name="Email")
	private String email;
	
	@Column(name="Username")
	private String username;
	
	@Column(name="Password")
	private String password;
	
	@Column(name="RoleName")
	private String roleName;
	
	@OneToMany(mappedBy="userJ", cascade= CascadeType.ALL)
	private List<Card> cards;

The error message is pretty clear. There is no field userId in your Card entity. Create one like that:

@Column(name = "UserId", insertable=false, updatable=false)
private Integer userId;

AFAIK, the problem seems to be that there's no userId column in the card table.