Fluent API and Loan Pattern/Execute around method Pattern

MessingAround.java

package com.example;

import java.io.IOException;
import java.util.function.Function;


public class MessingAround {

    public static void main(String[] args) throws IOException, InterruptedException {

        FluentMailer.send(mailer->mailer.to("[email protected]").from("[email protected]")
                .subject("Hello").body("Body!"));

    }

    public static class FluentMailer {
        private String addressTo,addressFrom,subject,message ;

        private FluentMailer() {
        }

        public static void send(final Function<FluentMailer,FluentMailer> block) {
            final FluentMailer mailer = new FluentMailer();
            FluentMailer result = block.apply(mailer);
            System.out.println(String.format("Sending email with: %s", result));
        }

        public FluentMailer from(final String address) {
            this.addressFrom = address;
            return this;
        }

        public FluentMailer to(final String address) {
            this.addressTo = address;
            return this;
        }

        public FluentMailer subject(final String subject) {
            this.subject = subject;
            return this;
        }

        public FluentMailer body(final String message) {
            this.message = message;
            return this;
        }

        @Override
        public String toString() {
            return "FluentMailer{" +
                    "addressTo='" + addressTo + '\'' +
                    ", addressFrom='" + addressFrom + '\'' +
                    ", subject='" + subject + '\'' +
                    ", message='" + message + '\'' +
                    '}';
        }
    }
}