@Entity
@Table(name = "role_permissions", schema = "sys")
@XmlRootElement
public class RolePermission implements Serializable {
    private static final long serialVersionUID = 1L;
    @EmbeddedId
    protected RolePermissionPK rolePermissionPK;
    @Basic(optional = false)
    @NotNull
    @ElementCollection
    @Column(name = "actions", nullable = false)
    private List<String> actions;

    ..... // getter and setters
}

@Embeddable
public class RolePermissionPK implements Serializable {
    @Basic(optional = false)
    @NotNull
    @Column(name = "role_id", nullable = false)
    private int roleID;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 32)
    @Column(name = "resource_key", nullable = false, length = 32)
    private String resourceKey;

    .... // getter and setters
}