Jack.java

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;


import java.util.Optional;

import static java.util.Objects.isNull;

public class User {
    final int id;
    final String firstName;
    final Optional<String> middleName;
    final String lastName;
    final int age;
    final long phone;
    final Optional<String> zip;


    @JsonCreator
    public User(
            @JsonProperty("id") int id,
            @JsonProperty("firstName")String firstName,
            @JsonProperty("middleName")String middleName,
            @JsonProperty("lastName")String lastName,
            @JsonProperty("age")int age,            
            @JsonProperty("phoneNumber")long phoneNumber,
            @JsonProperty("zip")String zip) {
        if (isNull(firstName) || isNull(lastName) ) {
            throw new NullPointerException((isNull(firstName) ? "firstName" : "lastName") + " is null");
        }
        this.id = id;
        this.firstName = firstName;
        this.middleName = Optional.ofNullable(middleName);
        if (this.middleName.isPresent() && !isPureString(middleName)) {
            throw new IllegalArgumentException("Middle name should be a string. Provided: " + middleName);
        }
        this.lastName = lastName;
        this.age = age;
        this.phone = phoneNumber;
        this.zip = Optional.ofNullable(zip);
    }

    //@JsonCreator
    public User(int id, String firstName, String lastName, int age, long phoneNumber) {
        this(id, firstName, null, lastName, age,  phoneNumber, null);
    }

    public int getId() {
        return id;
    }

    public String getFirstName() {
        return firstName;
    }

    public Optional<String> getMiddleName() {
        return middleName;
    }

    public String getLastName() {
        return lastName;
    }

    public int getAge() {
        return age;
    }


    public long getPhone() {
        return phone;
    }

    public Optional<String> getZip() {
        return zip;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof User)) return false;

        User user = (User) o;

        return id == user.id;

    }


}