jpa-buddy generates ddl schema with not all unique constraints

I have this entity:

@Getter
@Setter
@Entity
@Table(name = "publications")
public class Publication {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "publication_id")
    private Long id;
    @NotBlank
    @Column(name = "titie", nullable = false)
    private String title;
    @NotBlank
    @Column(name = "text", nullable = false, columnDefinition = "TEXT")
    private String text;
    @ManyToOne
    @JoinColumn(name = "author_username", nullable = false)
    private User author;
    @CreationTimestamp
    @Column(name = "publication_date", nullable = false)
    private Instant publicationDate;
    @OneToMany
    @JoinTable(
            name = "publications_files",
            uniqueConstraints = @UniqueConstraint(columnNames = {"file_id", "publication_id"}),
            joinColumns = @JoinColumn(name = "publication_id"),
            inverseJoinColumns = @JoinColumn(name = "file_id")
    )
    private List<File> files;
}

When I press "show DDL" and select PostgreSQL as my database it gives me the following result:

CREATE TABLE publications
(
    publication_id   BIGINT GENERATED BY DEFAULT AS IDENTITY NOT NULL,
    titie            VARCHAR(255)                            NOT NULL,
    text             TEXT                                    NOT NULL,
    author_username  VARCHAR(50)                             NOT NULL,
    publication_date TIMESTAMP WITHOUT TIME ZONE             NOT NULL,
    CONSTRAINT pk_publications PRIMARY KEY (publication_id)
);

CREATE TABLE publications_files
(
    file_id        BIGINT NOT NULL,
    publication_id BIGINT NOT NULL
);

ALTER TABLE publications_files
    ADD CONSTRAINT uc_publications_files_file UNIQUE (file_id);

ALTER TABLE publications
    ADD CONSTRAINT FK_PUBLICATIONS_ON_AUTHOR_USERNAME FOREIGN KEY (author_username) REFERENCES users (username);

ALTER TABLE publications_files
    ADD CONSTRAINT fk_pubfil_on_file FOREIGN KEY (file_id) REFERENCES files (file_id);

ALTER TABLE publications_files
    ADD CONSTRAINT fk_pubfil_on_publication FOREIGN KEY (publication_id) REFERENCES publications (publication_id);

I expected unique constraint for table publication_files with file_id and publication_id. But got just file_id in unique constraint. When I changed PostgreSQL to MySQL the result was the same. What do I wrong? Is it a bug ?

Yes, this is a bug, I created a ticket to fix it https://issues.jpa-buddy.com/issue/JPAB-2655

Also, if files collect unique elements, you can use Set instead of List - in this case JPA Buddy will generate a primary key for file_id + publication_id, and the unique constraint will not be needed.