Why is getter getting called for a transient field while saving in Spring data?

Question

I've a class like this:

public class User implements Serializable {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;

@Column(name = "units")
@Digits(integer = 9, fraction = 2)
@JsonIgnore
private BigDecimal units;

@Transient
private Balance userBalance;

public Balance getUserBalance() {
    return new Balance(this);
}

//...Code removed for brevity
}

Why is getter for userBalance getting called when I try to save my newly created User object, and that too multiple times ? I only want it to get called while serializing to json.