현재 로그인 중인 유저의 데이터 가져오기

기존 코드는 현재 로그인 중인 유저의 이름을 Spring security로 가져와 db에서 가져오는 코드였습니다. 
하지만 중복된 이름을 가진 유저가 발생해 쿼리 결과가 2개 이상 리턴이 되는 문제가 발생해 검색을 로그인 한 유저의 email로 db에서 찾아

리턴 하려고 합니다. 현재 로그인 중인 유저의 이름은 정상적으로 나오지만, email은 null값이 나와 이런 저런 코드를 수정해보고 채찍피티를 돌려도

항상 결과가 null 값입니다. 최근 몇주간 전혀 해결할 방법을 찾지못해 너무 답답합니다. 도와주세요~!!! ㅠㅠㅠ

package garabu.garabuServer.domain;

import jakarta.persistence.*;
import jakarta.validation.constraints.Email;
import lombok.Getter;
import lombok.Setter;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.UUID;

@Entity
@Getter @Setter
public class Member {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "member_id")
    private Long id;            // 회원 식별자 Id

    @Column(updatable = false, unique = true)
    private UUID uuid = UUID.randomUUID();  // 회원의 UUID

    private String username;        // 닉네임
    private String name;
    @Email
    private String email;       // 이메일
    private String password;         // 비번
    private String role;

    @OneToMany(mappedBy = "member")
    private List<UserBook> userBooks = new ArrayList<>();

}

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package garabu.garabuServer.service;

import garabu.garabuServer.domain.Book;
import garabu.garabuServer.domain.Member;
import garabu.garabuServer.jwt.CustomUserDetails;
import garabu.garabuServer.repository.BookRepository;
import garabu.garabuServer.repository.MemberJPARepository;
import lombok.RequiredArgsConstructor;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.UUID;

@Service
@RequiredArgsConstructor
public class BookService {

    private final BookRepository bookRepository;
    private final MemberJPARepository memberRepository;

    public Book createBook(String title) {
        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
        String currentUserName = authentication.getName();
        Member owner = memberRepository.findByUsername(currentUserName);

        Book book = new Book();
        book.setOwner(owner);
        book.setTitle(title);

        bookRepository.save(book);
        return book;
    }

    private String getEmail(){
        Authentication loggedInUser = SecurityContextHolder.getContext().getAuthentication();
        return loggedInUser.getName();
    }

    public List<Book> findLoggedInUserBooks() {
        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
        CustomUserDetails userDetails = (CustomUserDetails) authentication.getPrincipal();
        String email = userDetails.getEmail();

        System.out.println(authentication);
        System.out.println(userDetails                                         );
        System.out.println("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
        System.out.println(email);

        Member owner = memberRepository.findOneByEmail(email);
        return bookRepository.findByOwner(owner);
    }

    public Book findById(Long id) {
        return bookRepository.findById(id).orElseThrow(() -> new RuntimeException("Book not found"));
    }

    public Book findByTitle(String title) {
        return bookRepository.findByTitle(title);
    }
    //book. 가계부를 커플, 개인, 모임용으로 나누기 위해.
    //사용자 입력
    //가계부 이름 등록
    //

}

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package garabu.garabuServer.jwt;

import garabu.garabuServer.domain.Member;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.userdetails.UserDetails;

import java.util.ArrayList;
import java.util.Collection;
import java.util.UUID;

public class CustomUserDetails implements UserDetails {

    private final Member member;

    public CustomUserDetails(Member member) {

        this.member = member;
    }

    @Override
    public Collection<? extends GrantedAuthority> getAuthorities() {

        Collection<GrantedAuthority> collection = new ArrayList<>();

        collection.add(new GrantedAuthority() {

            @Override
            public String getAuthority() {

                return member.getRole();
            }
        });

        return collection;
    }

    @Override
    public String getPassword() {

        return member.getPassword();
    }

    @Override
    public String getUsername() {

        return member.getUsername();
    }

    public String getEmail() {

        return member.getEmail();
    }

    public UUID getUuid() {
        return member.getUuid();
    }

    @Override
    public boolean isAccountNonExpired() {

        return true;
    }

    @Override
    public boolean isAccountNonLocked() {

        return true;
    }

    @Override
    public boolean isCredentialsNonExpired() {

        return true;
    }

    @Override
    public boolean isEnabled() {

        return true;
    }
}

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package garabu.garabuServer.api;

import garabu.garabuServer.domain.Book;
import garabu.garabuServer.service.BookService;
import jakarta.validation.Valid;
import lombok.Data;
import lombok.RequiredArgsConstructor;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
@RequiredArgsConstructor
public class BookApiController {
    private final BookService bookService;

    @PostMapping("/api/v2/book")
    public CreateBookResponse saveBookV2(@RequestBody @Valid CreateBookRequest request) {
        // BookService 내에서 현재 로그인한 사용자를 기반으로 새로운 Book을 생성
        Book book = bookService.createBook(request.getTitle());
        return new CreateBookResponse(book.getId());
    }

    @GetMapping("/api/v2/book/mybooks")
    public ResponseEntity<List<Book>> getMyBooks() {
        List<Book> books = bookService.findLoggedInUserBooks();
        return ResponseEntity.ok(books);
    }

    @Data
    static class CreateBookRequest {
        private String title; // 가계부 이름
    }

    @Data
    static class CreateBookResponse {
        private Long id; // 생성된 가계부의 ID

        public CreateBookResponse(Long id) {
            this.id = id;
        }
    }
}

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package garabu.garabuServer.repository;

import garabu.garabuServer.domain.Member;
import org.springframework.data.jpa.repository.JpaRepository;

import java.util.List;

public interface MemberJPARepository extends JpaRepository<Member, Long> {
    List<Member> findByEmail(String email);
    Member findByUsername(String username);
    Member findOneByEmail(String email);
}