import java.io.*;
import java.util.*;
import java.util.List;
import java.util.ArrayList;
import org.apache.commons.lang3.builder.EqualsBuilder;
import java.util.stream.Collectors;

class Solution{

    private static final String DICTIONARY = "bob, robert\nliz, elizabeth\nben, benjamin\nnate, nathan, nathaniel\nandy, andrew\nchris, christopher\nalex, alexander";

    public static List<List<Person>> duplicates(List<Person> person){
    }
    
  	/**
     * The Person class
     */
    public static class Person {
  		private String firstName;
  		private String lastName;

  		public Person (String firstName, String lastName) {
  			this.firstName = firstName;
  			this.lastName = lastName;
  		}

  		public String getFirstName() {
  			return this.firstName;
  		}

  		public String getLastName() {
  			return this.lastName;
  		}
  
  		@Override
  		public String toString() {
  		  return String.format("%s %s", this.firstName, this.lastName);  
  		}
  
  		@Override
  		public boolean equals(Object o) {
  			if (this == o) {
  				return true;
  			}
  			if (o == null || getClass() != o.getClass()) {
  				return false;
  			}
  			Person that = (Person) o;
  			return new EqualsBuilder()
  				.append(firstName, that.firstName)
  				.append(lastName, that.lastName)
  				.build();
  		}

  		@Override
  		public int hashCode() {
  			return Objects.hash(firstName, lastName);
  		}
    }
}

Sample Input: 
List<Person> input = Arrays.asList(
    new Person("bob", "jones"), 
    new Person("noel", "smith"), 
    new Person("elizabeth", "smith"), 
    new Person("robert", "jones"),
    new Person("noel", "smith")
);

Expected Output:
Arrays.asList(
    Arrays.asList(new Person("noel", "smith"), new Person("noel", "smith")), 
    Arrays.asList(new Person("bob", "jones"), new Person("robert", "jones"))
  );