Hibernate single table inheritance creating columns for subclasses in springboot

Question

I am trying to implement hibernate Single table inheritance for a small project. Im using mariadb and springboot. I have defined a table called

xpense_raw_transactions

which is my single tabled for all bank transactions.

below is the table definition

DROP TABLE IF EXISTS `xpense_raw_transactions`;
CREATE TABLE IF NOT EXISTS `xpense_raw_transactions`(
`bank` varchar(31) NOT NULL,
`id` int(11) NOT NULL AUTO_INCREMENT,
`transactionDate` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
`narration` varchar(1024) NOT NULL,
`chqRefNo` varchar(256) DEFAULT NULL,
`fkSubXpenseCategory` int(11) DEFAULT NULL,
`withdrawalAmt` DECIMAL(10,2),
`depositAmt` DECIMAL(10,2),
`closingBalance` DECIMAL(10,2) DEFAULT 0,
 PRIMARY KEY (`id`)
);

here bank is the discriminator column.

When I persist the objects of the subclass, same columns are created with "_".

here is my spring jdbc configuration

#database properties
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/xpense
spring.datasource.username=root
spring.datasource.password=root
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.database-platform=org.hibernate.dialect.MySQL5InnoDBDialect

Here is my parent class

import lombok.*;

import javax.persistence.*;
import java.util.Date;

@Data
@AllArgsConstructor
@NoArgsConstructor
@Getter
@Setter
@Builder
@Entity
@Table(name="xpense_raw_transactions")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="bank",
    discriminatorType = DiscriminatorType.STRING)
public class DefaultRawTransaction {
    @Id
    @GeneratedValue(strategy= GenerationType.IDENTITY)
    private Integer id;
    @Column(name="transactionDate")
    private Date transactionDate;
    @Column(name="withdrawalAmt")
    private Double withdrawalAmt;
    @Column(name="depositAmt")
    private Double depositAmt;
    @Column(name="closingBalance")
    private Double closingBalance;
    @Column(name="fkSubXpenseCategory")
    private Integer fkSubXpenseCategory;
}

here is my sub class

package com.xpense.services.app.fileprocessing;

import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

import javax.persistence.Column;
import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;

@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor
@Entity
@DiscriminatorValue(value = "hdfc")
public class HdfcRawTransaction extends DefaultRawTransaction {
    @Column(name="narration")
    private String narration;
    @Column(name="chqRefNo")
    private String chqRefNo;
}

my jpa repository classes are as below:

@NoRepositoryBean
public interface DefaultRawTransactionRepository extends CrudRepository<DefaultRawTransaction,Integer> {
}

@Repository
public interface HdfcRawTransactionRepository extends DefaultRawTransactionRepository {

}

in my service class, I'm saving a list of my subclass objects

 @Override
public <S extends DefaultRawTransaction> List<S> uploadStatement(String type) {
    List<HdfcRawTransaction> transactions = new ArrayList<>();
    if ("PDF".equals(type)) {
     transactions = pdfFileProcessor.loadPdfFile(true);
     transactions = (List<HdfcRawTransaction>) hdfcRawTransactionRepository.saveAll(transactions);
    }

    return (List<S>) transactions;
}

when I save, new columns are created and the data is persisted. I want the data to be stored as per my table defination.

Is there something wrong? please help