store spring JPA repository find data to variable before save?

Question

i wanna store spring JPA repository object before it should be saved.

in function update, i wanna store old record data to dbDomain but suddenly after repository.save(updated) the dbDomain changed to new updated data.

any one know how to solve this ? thanks

package com.test.admintool.userauth.services;

import java.text.SimpleDateFormat;
import java.util.*;

import com.test.admintool.engine.common.AdminToolFunction;
import com.test.admintool.engine.common.AuditTrailMessage;
import com.test.admintool.engine.common.CopyUtil;
import com.test.admintool.engine.service.AdminService;
import com.test.admintool.engine.service.AuditTrailEventService;
import com.test.admintool.engine.utils.SecurityUtil;
import com.test.admintool.userauth.entity.User;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.extern.slf4j.Slf4j;
import org.springframework.core.GenericTypeResolver;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.transaction.annotation.Transactional;

import com.test.admintool.engine.AdminEntity;
import com.test.admintool.engine.exception.EntityNotFoundException;
import com.test.admintool.engine.repository.AdminRepository;
import com.querydsl.core.types.Predicate;

import javax.persistence.Entity;
import javax.persistence.EntityManager;
import javax.persistence.Table;

@Slf4j
public abstract class AdminServiceImpl<T extends AdminEntity<T>> implements AdminService<T> {

    private static final String AUDIT_ACTION_CREATE = "CREATE";
    private static final String AUDIT_ACTION_UPDATE = "UPDATE";
    private static final String AUDIT_ACTION_DELETE = "DELETE";
    private final AdminRepository<T> repository;

    private final AuditTrailEventService auditTrailEventService;

    protected AdminServiceImpl(AdminRepository<T> repository, AuditTrailEventService auditTrailEventService) {
        this.repository = repository;
        this.auditTrailEventService = auditTrailEventService;
    }

    public T get(Long id) throws EntityNotFoundException {
        return repository.findById(id)
                .orElseThrow(() -> new EntityNotFoundException(String.format("Product %s not found", id)));
    }

    @Transactional
    public T update(T updated) throws EntityNotFoundException {
        T dbDomain = get(updated.getId());
        T updatedData = repository.save(updated);
        produceAuditMessageUpdate(dbDomain, updatedData, AUDIT_ACTION_UPDATE);
        return updatedData;
    }
}