I have encountered the same problem. Please note that the issue occures only for default FetchMode which is JOIN. Please note that when you explicitly specify fetch mode as select @Fetch(FetchMode.SELECT) in your @ManyToOne relationship the correct query is generated e.g.:
@ManyToOne
@JoinColumn(name = "LEG_MATERIAL")
@Fetch(FetchMode.SELECT)
public MaterialType getLegsMaterial()

Please find also attached entire project with test cases which shows this behaviour.