I don't know why my normalize method is not passing the public test.

public class Passport $\{$

private String firstname;

private String middlename;

private String lastname;

private char separator $=\text{'},\text{'}$; $//$ Default separator

private StringBuffer stamps;

private static int objectCount $=0$;

$//$ Constructor with firstname, middlename, and lastname

public Passport$($String firstname, String middlename, String lastname$)\{$

this.firstname $=$ validateAndFormat$($firstname$)$;

this.middlename $=$ middlename.isBlank$()?""$ : validateAndFormat$($middlename$)$; $//$ Check for blank middle name

this.lastname $=$ validateAndFormat$($lastname$)$;

$//$ If any of the names are invalid, do not proceed with initialization

if $($this$.$firstname $==$ null $||$ this.lastname $==$ null$)\{$

return;

$\}$

this.stamps $=$ new StringBuffer$()$; $//$ Initialize stamps

objectCount$++$; $//$ Increment object count

$\}$

$//$ Constructor with firstname and lastname only, middle name is empty

public Passport$($String firstname, String lastname$)\{$

this$($firstname$,"",$ lastname$)$; $//$ Call the three$-$argument constructor

$\}$

$//$ Default constructor, uses default names

public Passport$()\{$

this$("$SAMPLEFIRSTNAME$",$ "SAMPLEMIDDLENAME", "SAMPLELASTNAME"$)$; $//$ Call the three$-$argument constructor

$\}$

$//$ Copy constructor

public Passport$($Passport passport$)\{$

this.firstname $=$ passport.firstname;

this.middlename $=$ passport.middlename;

this.lastname $=$ passport.lastname;

this.separator $=$ passport.separator;

this.stamps $=$ new StringBuffer$($passport$.$stamps$)$; $//$ Copy stamps

objectCount$++$; $//$ Increment object count

$\}$

$//$ toString method

@Override

public String toString$()\{$

String result $=$ lastname $+$ separator $+$ firstname;

if $(!$middlename.isEmpty$())\{$

result $+=$ separator $+$ middlename;

$\}$

return result;

$\}$

$//$ Method to add a stamp to the passport

public Passport addStamp$($String stamp$)\{$

if $($stamp $!=$ null && $!$stamp.isBlank$())\{$

stamps.append$($stamp$)$;

$\}$

return this; $//$ Return the current object

$\}$

$//$ Get a copy of the stamps

public StringBuffer getStamps$()\{$

return new StringBuffer$($stamps$)$; $//$ Return a copy of the stamps

$\}$

$//$ Get the separator

public char getSeparator$()\{$

return separator;

$\}$

$//$ Set the separator, ensuring the provided separator is valid

public boolean setSeparator$($char separator$)\{$

if $($separator $==\text{'}$@$\text{'}||$ Character.isSpaceChar$($separator$)||$ Character.isLetter$($separator$))\{$

return false; $//$ Invalid separator

$\}$

this.separator $=$ separator;

return true;

$\}$

$//$ Equals method to compare two Passport objects

@Override

public boolean equals$($Object obj$)\{$

if $($this $==$ obj$)$ return true;

if $($obj $==$ null $||$ getClass$()!=$ obj.getClass$())$ return false;

Passport passport $=($Passport$)$ obj;

return firstname.equals$($passport$.$firstname$)$ &&

middlename.equals$($passport$.$middlename$)$ &&

lastname.equals$($passport$.$lastname$)$;

$\}$

$//$ CompareTo method to compare passports alphabetically

public int compareTo$($Passport passport$)\{$

int lastNameComparison $=$ lastname.compareToIgnoreCase$($passport$.$lastname$)$;

if $($lastNameComparison $!=0)$ return lastNameComparison;

int firstNameComparison $=$ firstname.compareToIgnoreCase$($passport$.$firstname$)$;

if $($firstNameComparison $!=0)$ return firstNameComparison;

return middlename.compareToIgnoreCase$($passport$.$middlename$)$;

$\}$

$//$ Get the number of Passport objects created

public static int getNumberOfPassportObjects$()\{$

return objectCount;

$\}$

$//$ Reset the number of Passport objects created

public static void resetNumberOfPassportObjects$()\{$

objectCount $=0$;

$\}$

$//$ Normalize the passport $($uppercase or lowercase$)$

public static Passport normalize$($Passport passport, boolean uppercase$)\{$

if $($passport $==$ null$)$ return null;

String newFirstName $=$ uppercase $?$ passport.firstname.toUpperCase$()$ : passport.firstname.toLowerCase$()$;

String newMiddleName $=$ uppercase $?$ passport.middlename.toUpperCase$()$ : passport.middlename.toLowerCase$()$;

String newLastName $=$ uppercase $?$ passport.lastname.toUpperCase$()$ : passport.lastname.toLowerCase$()$;

Passport normalizedPassport $=$ new Passport$($newFirstName$,$ newMiddleName, newLastName$)$;

normalizedPassport.setSeparator$($passport$.$getSeparator$())$; $//$ Preserve the separator

return normalizedPassport;

$\}$

normalize

public static Passport normalize$($Passport passport,

boolean uppercase$)$ method will return null and perform no processing.

Parameters: $\backslash (\backslash$square $\backslash )$

passport $-$ Passport reference.

uppercase $-$ If true turn to uppercase; otherwise l $```$

Driver

public class Driver $\{$

public static void main$($String$[]$ args$)\{$

Passport.resetNumberOfPassportObjects$()$;

Passport passport$1=$ new Passport$("$claudia$",$ "I.", "smith"$)$;

System.out.println$($passport$1)$;

Passport passport$2=$ new Passport$("$John$",$ "RoberTs"$)$;

System.out.println$($passport$2)$;

Passport passport$3=$ new Passport$()$;

System.out.println$($passport$3)$;

System.out.println$("=============")$;

passport$1.$addStamp$("$Spain$")$;

passport$1.$addStamp$("$London$")$;

System.out.println$("$Stamps for $"+$ passport$1+"-->"+$ passport$1.$getStamps$())$;

passport$1.$setSeparator$(\text{'}$#$\text{'})$;

System.out.println$($passpo $```$

@Test

public v