Employee Builder

package com.clients.erp;

public class Employee {

    private final int id;
    private final String ssn, lastName, firstName;
    private final String address1, address2, city, state, zip, phone1, phone2;

    public static class Builder {

        private final int id;
        private final String ssn;
        private final String lastName;
        private final String firstName;

        private String address1 = null;
        private String address2 = null;
        private String city = null;
        private String state = null;
        private String zip = null;
        private String phone1 = null;
        private String phone2 = null;


            // required parameters

            public Builder(int id, String ssn, String lastName, String firstName) {
                this.id = id;
                this.ssn = ssn;
                this.lastName = lastName;
                this.firstName = firstName;
            }

            // optional parameters

            public Builder address1 (String val) { address1 = val; return this; }
            public Builder address2 (String val) { address2 = val; return this; }
            public Builder city (String val) { city = val; return this; }
            public Builder state (String val) { state = val; return this; }
            public Builder zip (String val) { zip = val; return this; }
            public Builder phone1 (String val) { phone1 = val; return this; }
            public Builder phone2 (String val) { phone2 = val; return this; }

            public Employee build() {
                return new Employee(this);
            }
        }

        private Employee(Builder builder) {
            id = builder.id;
            ssn = builder.ssn;
            lastName = builder.lastName;
            firstName = builder.firstName;
            address1 = builder.address1;
            address2 = builder.address2;
            city = builder.city;
            state = builder.state;
            zip = builder.zip;
            phone1 = builder.phone1;
            phone2 = builder.phone2;

        }

        @Override
        public String toString() {
            return "Employee [id=" + id + ", ssn=" + ssn + ", lastName=" + lastName + ", firstName=" + firstName
                    + ", address1=" + address1 + ", address2=" + address2 + ", city=" + city + ", state=" + state
                    + ", zip=" + zip + ", phone1=" + phone1 + ", phone2=" + phone2 + "]";
        }
    }