La conversion POJO en JSON ne fonctionne pas pour la variable String commençant par "is"

La variable de chaîne - "isInitial" dans l'exemple ci-dessous n'est pas convertie en JSON. Est-il possible de générer une structure JSON pour la variable isInitial sans modifier la classe EmployeePOJO ?

PS: la conversion de la méthode getter en getIsInitial fonctionne.

Veuillez trouver ci-dessous la classe POJO utilisée pour générer le JSON:

import org.codehaus.jackson.map.ObjectMapper;

import java.io.IOException;

public class JacksonPojoToJson {
    public static void main(String[] args) throws IOException {
        // Create ObjectMapper
        ObjectMapper mapper = new ObjectMapper();

        EmployeePOJO employeePOJO = new EmployeePOJO();
        employeePOJO.setFirstName("FIRST NAME");
        employeePOJO.setFirstNameAvailable(true);
        employeePOJO.setLastName("last name");
        employeePOJO.setHasLastNameAvailable(true);
        employeePOJO.setInitial("true");

        // Convert object to JSON string
        String json = mapper.writeValueAsString(employeePOJO);
        System.out.println(json);
    }
}

Veuillez trouver ci-dessous la logique principale de la conversion POJO:

public class EmployeePOJO {
    private String firstName;
    private String lastName;
    private String isInitial;
    private boolean isFirstNameAvailable;
    private boolean hasLastNameAvailable;
    private String hasHouse;


    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String isInitial()
    {
        return this.isInitial;
    }

    public void setInitial(String pInitial)
    {
        this.isInitial = pInitial;
    }

    public String getHasHouse() {
        return hasHouse;
    }

    public void setHasHouse(String hasHouse) {
        this.hasHouse = hasHouse;
    }

    public boolean isFirstNameAvailable() {
        return isFirstNameAvailable;
    }

    public void setFirstNameAvailable(boolean firstNameAvailable) {
        isFirstNameAvailable = firstNameAvailable;
    }

    public boolean isHasLastNameAvailable() {
        return hasLastNameAvailable;
    }

    public void setHasLastNameAvailable(boolean hasLastNameAvailable) {
        this.hasLastNameAvailable = hasLastNameAvailable;
    }
}