Customer constructor
Customer()
Implementation
Customer(this.id, this.firstName, this.secondName, this.email, this.mobile,
this.city, this.country, this.postalCode, this.street, this.state) {
this.id = id;
this.firstName = firstName;
this.secondName = secondName;
this.email = email;
this.mobile = mobile;
this.city = city;
this.country = country;
this.postalCode = postalCode;
this.street = street;
this.state = state;
}