Unable to locate DTO in Spring Boot Application

I have defined my DTO then also it can't locate it.
I have created DTO in entities package and just imported the package wherever I needed it didn't give any error while compiling it gave error while running the code it occured after Initializing JPA EntityManagerFactory why so please help me out.

> CartDTO file

package com.project.books.entity;

public class CartDTO {

	private String name;
	private String username;
	private String status;
	private int price;
	
	public CartDTO() {
		
	}
	
	public CartDTO(String name, String username, String status, int price) {
		this.name = name;
		this.username = username;
		this.status = status;
		this.price = price;
	}
	
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getStatus() {
		return status;
	}
	public void setStatus(String status) {
		this.status = status;
	}
	public int getPrice() {
		return price;
	}
	public void setPrice(int price) {
		this.price = price;
	}
	
	
}

> cartRepository file

package com.project.books.dao;

import java.util.List;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;

import com.project.books.entity.Cart;
import com.project.books.entity.CartDTO;

public interface CartRepository extends JpaRepository<Cart,Integer> {

	@Query("select c from Cart c where c.username = :username AND c.status = :status")
	public List<Cart> findAllByUsernameAndStatus(@Param("username")String username,
												@Param("status")String status);
	
	
	@Query("select new CartDTO(c.name,c.username,c.status,sum(c.price)) from Cart c where c.username = :username AND c.status = :status GROUP BY username,status")
	public CartDTO sumPriceByUsernameAndStatus(@Param("username")String username,
												@Param("status")String status);
}

> Myerror

Unable to locate class [CartDTO]
	at org.hibernate.hql.internal.ast.tree.ConstructorNode.resolveConstructor(ConstructorNode.java:177) ~[hibernate-core-5.4.18.Final.jar:5.4.18.Final]
	at org.hibernate.hql.internal.ast.tree.ConstructorNode.prepare(ConstructorNode.java:144) ~[hibernate-core-5.4.18.Final.jar:5.4.18.Final]
	at org.hibernate.hql.internal.ast.HqlSqlWalker.processConstructor(HqlSqlWalker.java:1258) ~[hibernate-core-5.4.18.Final.jar:5.4.18.Final]


 Error creating bean with name 'cartRepository': FactoryBean threw exception on object creation; nested exception is java.lang.IllegalArgumentException: Validation failed for query for method public abstract com.project.books.entity.CartDTO com.project.books.dao.CartRepository.sumPriceByUsernameAndStatus(java.lang.String,java.lang.String)!
	at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:176) ~[spring-beans-5.2.8.RELEASE.jar:5.2.8.RELEASE]
	at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.getObjectFromFactoryBean(FactoryBeanRegistrySupport.java:101) ~[spring-beans-5.2.8.RELEASE.jar:5.2.8.RELEASE]



 Validation failed for query for method public abstract com.project.books.entity.CartDTO com.project.books.dao.CartRepository.sumPriceByUsernameAndStatus(java.lang.String,java.lang.String)!
	at org.springframework.data.jpa.repository.query.SimpleJpaQuery.validateQuery(SimpleJpaQuery.java:93) ~[spring-data-jpa-2.3.2.RELEASE.jar:2.3.2.RELEASE]

 Unable to locate class [CartDTO] [select new CartDTO(c.name,c.username,c.status,sum(c.price)) from com.project.books.entity.Cart c where c.username = :username AND c.status = :status GROUP BY username,status]
	at org.hibernate.hql.internal.ast.QuerySyntaxException.convert(QuerySyntaxException.java:74) ~[hibernate-core-5.4.18.Final.jar:5.4.18.Final]
	at org.hibernate.hql.internal.ast.ErrorTracker.throwQueryException(ErrorTracker.java:93) ~[hibernate-core-5.4.18.Final.j

Please help me resolve it.
Let me tell you by this query what I meant to do I just needed sum of all prices where username is the user logged in and status is some string.

You must use the fully qualified name:

@Query("select new com.project.books.entity.CartDTO(c.name,c.username,c.status,sum(c.price)) from Cart c where c.username = :username AND c.status = :status GROUP BY username,status")
public CartDTO sumPriceByUsernameAndStatus(@Param("username")String username,
                                            @Param("status")String status);

When you query for Entities you can use the Entity name that's if not set the simple name of the Class.

But with DTOs there is no such name so you have to use the fully qualified name.

Additionally you have to change the constructor to

public CartDTO(String name, String username, String status, long price) {

Because sum returns long.