我尝试使用spring data jpa和spring Boot 读取oracle存储过程中的refcursor，存储过程运行成功，但对返回的List的引用始终为空。
我尝试使用Hibernate作为JPA提供程序和Eclipse链接，但没有成功，下面是oracle ddl和java代码
Oracle表（我在表中填充了一些示例数据）

CREATE TABLE role
    (id                             NUMBER(10,0),
    name                           VARCHAR2(255 CHAR))

Oracle存储过程

PROCEDURE collect_roles (role_list_o OUT SYS_REFCURSOR) IS
    ex EXCEPTION;
BEGIN
    OPEN role_list_o FOR SELECT id, name FROM role;
END;

pom.xml（Oracle jdbc驱动程序依赖项已从本地ojdbc7.jar安装到maven中）

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
    http://maven.apache.org/maven-v4_0_0.xsd"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <modelVersion>4.0.0</modelVersion>

<groupId>org.springframework</groupId>
<artifactId>gridapp</artifactId>
<version>0.1.0</version>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.5.RELEASE</version>
</parent>

<properties>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>

    <!-- Oracle JDBC driver -->
    <dependency>
        <groupId>com.oracle</groupId>
        <artifactId>ojdbc7</artifactId>
        <version>12.1.0</version>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>
</project>

application.properties

spring.main.banner-mode=off

# Oracle settings

spring.datasource.url=jdbc:ora_string_conection
spring.datasource.username=username
spring.datasource.password=password
spring.datasource.driver-class-oracle.jdbc.driver.OracleDriver

# HikariCP settings

# spring.datasource.hikari.*

spring.datasource.hikari.connection-timeout=60000
spring.datasource.hikari.maximum-pool-size=5

Role.java

package hello;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.NamedStoredProcedureQueries;
import javax.persistence.NamedStoredProcedureQuery;
import javax.persistence.ParameterMode;
import javax.persistence.StoredProcedureParameter;
import javax.persistence.Table;

import org.springframework.data.domain.Sort.Direction;

@NamedStoredProcedureQueries({
@NamedStoredProcedureQuery(name = "findRolesViaProcedure",
    procedureName = "wfactura.collect_roles",
    resultClasses = Role.class,
    parameters = {
        @StoredProcedureParameter(mode = ParameterMode.REF_CURSOR, name = "role_list_o", type = Void.class)

    })})
@Entity
public class Role {

    @Id @GeneratedValue//
    @Column(name="ID")
    private Long id;

    @Column(name="NAME")
    private String name;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

RoleRepository.java

package hello;

import java.io.Serializable;
import java.util.List;

import org.springframework.data.jpa.repository.query.Procedure;
import org.springframework.data.repository.CrudRepository;

interface RoleRepository extends CrudRepository<Role, Serializable> {

    @Procedure(name = "findRolesViaProcedure")
    List<Role> findRolesViaProcedure();

}

我用下一行调用存储过程

List<Role> roles = repo.findRolesViaProcedure();

我修改了在另一个表中插入值的存储过程，并且我意识到执行成功，但是List roles为空，即使表中有数据。
有人能帮帮我吗？