основная таблица
@OneToMany(mappedBy="document", fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval=true)
@SerializedName(value = "transactions")
private List<DocumentTransaction> documentTransactions;

подчиненная таблица
@ManyToOne(fetch = FetchType.LAZY, optional = false)
@JoinColumn(name="document_id")
@OnDelete(action = OnDeleteAction.CASCADE)
private Document document;