Please help me debug this code

import java.util.Objects;

public class SortedTreeSet implements SortedTreeSetInterface $\{$

private Person data;

private SortedTreeSet left;

private SortedTreeSet right;

public SortedTreeSet$()\{$

this.data $=$ null; # Represents an empty tree

$\}$

@Override

public Person getPerson$()\{$

return data;

$\}$

@Override

public boolean hasLeft$()\{$

return left $!=$ null;

$\}$

@Override

public void setLeft$($SortedTreeSet left$)\{$

this.left $=$ left;

$\}$

@Override

public SortedTreeSet getLeft$()\{$

return left;

$\}$

@Override

public boolean hasRight$()\{$

return right $!=$ null;

$\}$

@Override

public void setRight$($SortedTreeSet right$)\{$

this.right $=$ right;

$\}$

@Override

public SortedTreeSet getRight$()\{$

return right;

$\}$

# Add a Person to the tree while keeping it sorted and free of duplicates

@Override

public void add$($Person p$)\{$

if $($data $==$ null$)\{$

data $=$ p; # First node added to the tree

return;

$\}$

int compare $=$ p$.$getName$().$compareTo$($data$.$getName$())$;

if $($compare $<0)\{$ # p$\text{'}$s name is smaller, go to the left subtree

if $($left $==$ null$)\{$

left $=$ new SortedTreeSet$()$;

$\}$

left.add$($p$)$;

$\}$ else if $($compare $>0)\{$ # p$\text{'}$s name is larger, go to the right subtree

if $($right $==$ null$)\{$

right $=$ new SortedTreeSet$()$;

$\}$

right.add$($p$)$;

$\}$

# If compare $==0,$ it's a duplicate, so we do nothing

$\}$

# Optional: To print the tree's content in sorted order

@Override

public String toString$()\{$

StringBuilder sb $=$ new StringBuilder$()$;

if $($left $!=$ null$)$ sb$.$append$($left$.$toString$())$;

if $($data $!=$ null$)$ sb$.$append$($data$).$append$("$

$")$;

if $($right $!=$ null$)$ sb$.$append$($right$.$toString$())$;

return sb$.$toString$()$;

$\}$

$\}$