What to do when a javax.el.PropertyNotWritableException occurs

Event: I was angry that I could not set a value for Bean when I executed submit processing from the screen

--Environment --Windows10 64bit version 1909 - openjdk 11 2018-09-25 - Eclipse IDE for Enterprise Java Developers Version: 2020-09 (4.17.0) - JSF 2.3.9 - Payara Server 5.194

javax.el.PropertyNotWritableException: /admin/ponsuke/ponsuke.xhtml @52,92 value="#{item.mailAddress}": The class 'jp.co.my.app.Item' does not have a writable property 'mailAddress'.
    at com.sun.faces.facelets.el.TagValueExpression.setValue(TagValueExpression.java:99)
    at javax.faces.component.UIInput.updateModel(UIInput.java:859)
    at javax.faces.component.UIInput.processUpdates(UIInput.java:773)
    at com.sun.faces.facelets.component.UIRepeat.process(UIRepeat.java:571)

To Bean ...

<!--abridgement-->
  <ui:repeat var="category" varStatus="index" value="#{ponsukeController.categories}">
    <ui:repeat var="item" varStatus="status" value="#{category.itemList}">
        <td class="form-inline">
          <h:inputText value="#{item.mailAddress}" />
<!--abridgement-->

No Setter?

PonsukeController

//abridgement
/**Category information list. */
@Getter
@Setter
private List<Category> categories;
//abridgement

Cause: The child class does not have @Setter

Ahhhh, @ Value didn't include @ Setter ...

In practice, @Value is shorthand for: final @ToString @EqualsAndHashCode @AllArgsConstructor @FieldDefaults(makeFinal = true, level = AccessLevel.PRIVATE) @Getter, except that explicitly including an implementation of any of the relevant methods simply means that part won't be generated and no warning will be emitted. @Value - projectlombok.org

Category

import lombok.Value;

@Value
public class Category {
    List<Item> itemList;
}

Item

import lombok.Value;

@Value
public class Item {
    int itemId;
    String mailAddress;
}

Action: Change the annotation of the class with the property to be set

This time @Value is stuck and I'm using the role of @AllArgsConstructor elsewhere, so [@Getter @AllArgsConstructor] + [@Setter] = [@Data @AllArgsConstructor] I decided to change to. Since the property of class Category is List and only the contents are changed, the annotation is not changed.

Item

import lombok.AllArgsConstructor;
import lombok.Data;

@Data
@AllArgsConstructor
public class Item {
//abridgement

By the way If you add @Setter to each of the ʻitemList and mailAddressproperties, a compile error will occur. PropertyNotWritableException occurred even if@Setter was added to class in addition to @Value. I think it's because there is @FieldDefaults (makeFinal = true, level = AccessLevel.PRIVATE)`.

To add final to each (instance) field, use @FieldDefaults(makeFinal=true). Any non-final field which must remain nonfinal can be annotated with @NonFinal (also in the lombok.experimental package). @FieldDefaults - projectlombok.org