OneToMany and ManyToOne annotations

@OneToMany(cascade=ALL, mappedBy="customer")
Set<Order> orders;

1. targetEntity : Used to specify the class of the target entity.
   Must be specified if class is not specified in generic.
   For example,
   It must be specified for field:

   Set children;
   

   It should not be specified for field:

   Set<Child> children;
   

   
   
2. mappedBy : Denotes the "field" in the "other" table whose primary-key is present as foreign-key in the "other" table.
   Example:

   @OneToMany(cascade=ALL, mappedBy="customer")
   Set<Order> orders;
   

   The mappedBy property will not work if there is no matching annotation on the entity on the other side.
   In the above case, the foreign key must be present as @ManyToOne annotation on the field "customer" in the entity "Order".

   @ManyToOne
   @JoinColumn(name="CUST_ID", nullable=false)
   Customer customer;