How it works...

Let's check each declared constraint:

    @NotBlank (message = "Name should not be blank")
    @Size (min = 4, max = 10,message = "Name should be between 
           4 and 10 characters")
    private String name;

The @NotBlank annotation will deny not only null values, but also whitespace values, and @Size speaks for itself:

    @Email (message = "Invalid e-mail format")
    @NotBlank (message = "E-mail shoud not be blank")
    private String email;

The @Email constraint will check the email string format:

    @PastOrPresent (message = "Created date should be past or present")
    @NotNull (message = "Create date should not be null")
    private LocalDate created;

@PastOrPresent will constrain LocalDate to be in the past or until the present date. It can't be in the future.

Here, we can't use @NotBlank as there is no blank date, only null, so we avoid this by using @NotNull:

    @Future (message = "Expires should be a future date")
    @NotNull (message = "Expires should not be null")
    private LocalDate expires;

This is the same as the preceding constraint, but constraints for a future date.

In our UI, there are two places we should take a careful look at:

 <h:inputText id="created" value="#{user.created}">
     <f:convertDateTime type="localDate" pattern="dd/MM/uuuu" /> 
 </h:inputText>

 ...

 <h:inputText id="expire" value="#{user.expires}">
     <f:convertDateTime type="localDate" pattern="dd/MM/uuuu" /> 
 </h:inputText>

Here, we are using convertDateTime to automatically convert the data that's inputted into inputText according to the dd/MM/uuuu pattern.