SpringBoot stores data in h2 , but failed to retrieve the data and show it in JSON format in browser or postman

I have done lots of research on internet for two consecutive days, but don't understand what is happening.

In my personal project, I have a Payment and Bill entity. Payment can contain many Bills (One-to-Many), but Bill can contain only one Payment (Many-to-One).

Data stored in the H2 database nicely, but when i returned the data in JSON format it just shows nothing!

This is my first question in stackoverflow, if I did any mistake pls correct me. Any suggestion will be helpful.

POM.xml

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

    <groupId>com.example.HospitalManagementSystem</groupId>
    <artifactId>HospitalManagementSystem</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>HospitalManagementSystem</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-test</artifactId>
            <scope>test</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.tomcat/tomcat-jasper -->
        <dependency>
            <groupId>org.apache.tomcat</groupId>
            <artifactId>tomcat-jasper</artifactId>
            <version>8.5.31</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.tomcat.embed/tomcat-embed-jasper -->
        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
            </dependency>

        <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.dataformat/jackson-dataformat-xml -->
        <dependency>
            <groupId>com.fasterxml.jackson.dataformat</groupId>
            <artifactId>jackson-dataformat-xml</artifactId>
        </dependency>

    </dependencies>

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


</project>

Payment.java

    package com.example.HospitalManagementSystem.HospitalManagementSystem.Model;

import lombok.Data;
import org.springframework.beans.factory.annotation.Autowired;

import javax.persistence.*;
import javax.validation.constraints.NotNull;
import java.util.HashSet;
import java.util.Set;


@Entity

public class Payment {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    //private int Amount;
    @Column
    private String Type;

    @OneToMany(mappedBy = "payment", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private Set<Bill> Bills;

    public Payment() {
    }

    public Payment(String Type) {
        this.Type=Type;
    }

}

Bill.java

    package com.example.HospitalManagementSystem.HospitalManagementSystem.Model;


import com.fasterxml.jackson.annotation.JsonBackReference;
import javax.persistence.*;

@Entity

public class Bill {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    @Column
    private String Amount;

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "payment_id")
    @JsonBackReference
    private Payment payment;

    public Bill() {
    }

    public Bill(String Amount){
        //this.id=BillId;
        this.Amount=Amount;
    }

    public Bill(String amount, Payment payment) {
        Amount = amount;
        this.payment = payment;
    }
}

BillRepo.java

 package com.example.HospitalManagementSystem.HospitalManagementSystem.Repository;

import com.example.HospitalManagementSystem.HospitalManagementSystem.Model.Bill;
import org.springframework.data.jpa.repository.JpaRepository;

public interface BillRepo extends JpaRepository<Bill, Integer> {
}

PaymentRepo.java

    package com.example.HospitalManagementSystem.HospitalManagementSystem.Repository;

import com.example.HospitalManagementSystem.HospitalManagementSystem.Model.Payment;
import org.springframework.data.jpa.repository.JpaRepository;

public interface PaymentRepo extends JpaRepository<Payment, Integer> {
}

myController.java

    package com.example.HospitalManagementSystem.HospitalManagementSystem.Controller;

import com.example.HospitalManagementSystem.HospitalManagementSystem.Model.Bill;
import com.example.HospitalManagementSystem.HospitalManagementSystem.Model.Payment;
import com.example.HospitalManagementSystem.HospitalManagementSystem.Repository.BillRepo;
import com.example.HospitalManagementSystem.HospitalManagementSystem.Repository.PaymentRepo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;

@RestController
public class myController {
    @Autowired
    PaymentRepo paymentRepo;

    @Autowired
    BillRepo billRepo;

    @GetMapping("/welcome")
    public void enterData(){
        Payment p1=new Payment("abc");
        Payment p2=new Payment("abc");
        Payment p3=new Payment("abc");

        paymentRepo.save(p1);
        paymentRepo.save(p2);
        paymentRepo.save(p3);

        Bill b1=new Bill("100", p1);
        Bill b2=new Bill("200", p1);
        Bill b3=new Bill("300", p2);

        billRepo.save(b1);
        billRepo.save(b2);
        billRepo.save(b3);

    }


    @GetMapping("/goodbye")
    public List<Bill> getData(){
        List<Payment> paymentList=paymentRepo.findAll();
        List<Bill> billList=billRepo.findAll();

        System.out.println("<----------------- Payment List ------------------>  " + paymentList.size());
        paymentList.forEach(System.out::println);

        System.out.println("<----------------- Bill List ------------------>  " + billList.size());
        billList.forEach(System.out::println);

        return billList;
    }
}

Figure 1: Bill table enter image description here

Figure 2: Payment table enter image description here

Figure 3: postmant showing no data enter image description here

and finally here is the console log:

org.springframework.http.ResponseEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryPropertyReferenceController.followPropertyReference(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,java.lang.String,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler) throws java.lang.Exception
2018-08-15 15:44:04.526  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}/{property}/{propertyId}],methods=[GET],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryPropertyReferenceController.followPropertyReference(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,java.lang.String,java.lang.String,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler) throws java.lang.Exception
2018-08-15 15:44:04.526  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}/{property}],methods=[DELETE],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<? extends org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryPropertyReferenceController.deletePropertyReference(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,java.lang.String) throws java.lang.Exception
2018-08-15 15:44:04.527  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}/{property}],methods=[GET],produces=[application/x-spring-data-compact+json || text/uri-list]}" onto public org.springframework.http.ResponseEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryPropertyReferenceController.followPropertyReferenceCompact(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,java.lang.String,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler) throws java.lang.Exception
2018-08-15 15:44:04.527  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}/{property}],methods=[PATCH || PUT || POST],consumes=[application/json || application/x-spring-data-compact+json || text/uri-list],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<? extends org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryPropertyReferenceController.createPropertyReference(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.http.HttpMethod,org.springframework.hateoas.Resources<java.lang.Object>,java.io.Serializable,java.lang.String) throws java.lang.Exception
2018-08-15 15:44:04.527  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}/{property}/{propertyId}],methods=[DELETE],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryPropertyReferenceController.deletePropertyReferenceId(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,java.lang.String,java.lang.String) throws java.lang.Exception
2018-08-15 15:44:04.528  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/ || ],methods=[OPTIONS],produces=[application/hal+json || application/json]}" onto public org.springframework.http.HttpEntity<?> org.springframework.data.rest.webmvc.RepositoryController.optionsForRepositories()
2018-08-15 15:44:04.529  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/ || ],methods=[HEAD],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositoryController.headForRepositories()
2018-08-15 15:44:04.529  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/ || ],methods=[GET],produces=[application/hal+json || application/json]}" onto public org.springframework.http.HttpEntity<org.springframework.data.rest.webmvc.RepositoryLinksResource> org.springframework.data.rest.webmvc.RepositoryController.listRepositories()
2018-08-15 15:44:04.531  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search],methods=[OPTIONS],produces=[application/hal+json || application/json]}" onto public org.springframework.http.HttpEntity<?> org.springframework.data.rest.webmvc.RepositorySearchController.optionsForSearches(org.springframework.data.rest.webmvc.RootResourceInformation)
2018-08-15 15:44:04.532  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search/{search}],methods=[GET],produces=[application/x-spring-data-compact+json]}" onto public org.springframework.hateoas.ResourceSupport org.springframework.data.rest.webmvc.RepositorySearchController.executeSearchCompact(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.http.HttpHeaders,org.springframework.util.MultiValueMap<java.lang.String, java.lang.Object>,java.lang.String,java.lang.String,org.springframework.data.rest.webmvc.support.DefaultedPageable,org.springframework.data.domain.Sort,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler)
2018-08-15 15:44:04.532  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search],methods=[HEAD],produces=[application/hal+json || application/json]}" onto public org.springframework.http.HttpEntity<?> org.springframework.data.rest.webmvc.RepositorySearchController.headForSearches(org.springframework.data.rest.webmvc.RootResourceInformation)
2018-08-15 15:44:04.532  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search],methods=[GET],produces=[application/hal+json || application/json]}" onto public org.springframework.data.rest.webmvc.RepositorySearchesResource org.springframework.data.rest.webmvc.RepositorySearchController.listSearches(org.springframework.data.rest.webmvc.RootResourceInformation)
2018-08-15 15:44:04.533  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search/{search}],methods=[GET],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositorySearchController.executeSearch(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.util.MultiValueMap<java.lang.String, java.lang.Object>,java.lang.String,org.springframework.data.rest.webmvc.support.DefaultedPageable,org.springframework.data.domain.Sort,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler,org.springframework.http.HttpHeaders)
2018-08-15 15:44:04.533  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search/{search}],methods=[OPTIONS],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<java.lang.Object> org.springframework.data.rest.webmvc.RepositorySearchController.optionsForSearch(org.springframework.data.rest.webmvc.RootResourceInformation,java.lang.String)
2018-08-15 15:44:04.533  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/search/{search}],methods=[HEAD],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<java.lang.Object> org.springframework.data.rest.webmvc.RepositorySearchController.headForSearch(org.springframework.data.rest.webmvc.RootResourceInformation,java.lang.String)
2018-08-15 15:44:04.535  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}],methods=[OPTIONS],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositoryEntityController.optionsForCollectionResource(org.springframework.data.rest.webmvc.RootResourceInformation)
2018-08-15 15:44:04.535  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}],methods=[HEAD],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositoryEntityController.headCollectionResource(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.data.rest.webmvc.support.DefaultedPageable) throws org.springframework.web.HttpRequestMethodNotSupportedException
2018-08-15 15:44:04.535  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}],methods=[GET],produces=[application/hal+json || application/json]}" onto public org.springframework.hateoas.Resources<?> org.springframework.data.rest.webmvc.RepositoryEntityController.getCollectionResource(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.data.rest.webmvc.support.DefaultedPageable,org.springframework.data.domain.Sort,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler) throws org.springframework.data.rest.webmvc.ResourceNotFoundException,org.springframework.web.HttpRequestMethodNotSupportedException
2018-08-15 15:44:04.536  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}],methods=[GET],produces=[application/x-spring-data-compact+json || text/uri-list]}" onto public org.springframework.hateoas.Resources<?> org.springframework.data.rest.webmvc.RepositoryEntityController.getCollectionResourceCompact(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.data.rest.webmvc.support.DefaultedPageable,org.springframework.data.domain.Sort,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler) throws org.springframework.data.rest.webmvc.ResourceNotFoundException,org.springframework.web.HttpRequestMethodNotSupportedException
2018-08-15 15:44:04.536  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}],methods=[POST],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryEntityController.postCollectionResource(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.data.rest.webmvc.PersistentEntityResource,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler,java.lang.String) throws org.springframework.web.HttpRequestMethodNotSupportedException
2018-08-15 15:44:04.536  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}],methods=[OPTIONS],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositoryEntityController.optionsForItemResource(org.springframework.data.rest.webmvc.RootResourceInformation)
2018-08-15 15:44:04.536  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}],methods=[HEAD],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositoryEntityController.headForItemResource(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler) throws org.springframework.web.HttpRequestMethodNotSupportedException
2018-08-15 15:44:04.537  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}],methods=[PATCH],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryEntityController.patchItemResource(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.data.rest.webmvc.PersistentEntityResource,java.io.Serializable,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler,org.springframework.data.rest.webmvc.support.ETag,java.lang.String) throws org.springframework.web.HttpRequestMethodNotSupportedException,org.springframework.data.rest.webmvc.ResourceNotFoundException
2018-08-15 15:44:04.537  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}],methods=[DELETE],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.data.rest.webmvc.RepositoryEntityController.deleteItemResource(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,org.springframework.data.rest.webmvc.support.ETag) throws org.springframework.data.rest.webmvc.ResourceNotFoundException,org.springframework.web.HttpRequestMethodNotSupportedException
2018-08-15 15:44:04.537  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}],methods=[PUT],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<? extends org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.RepositoryEntityController.putItemResource(org.springframework.data.rest.webmvc.RootResourceInformation,org.springframework.data.rest.webmvc.PersistentEntityResource,java.io.Serializable,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler,org.springframework.data.rest.webmvc.support.ETag,java.lang.String) throws org.springframework.web.HttpRequestMethodNotSupportedException
2018-08-15 15:44:04.537  INFO 3920 --- [  restartedMain] o.s.d.r.w.RepositoryRestHandlerMapping   : Mapped "{[/{repository}/{id}],methods=[GET],produces=[application/hal+json || application/json]}" onto public org.springframework.http.ResponseEntity<org.springframework.hateoas.Resource<?>> org.springframework.data.rest.webmvc.RepositoryEntityController.getItemResource(org.springframework.data.rest.webmvc.RootResourceInformation,java.io.Serializable,org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler,org.springframework.http.HttpHeaders) throws org.springframework.web.HttpRequestMethodNotSupportedException
2018-08-15 15:44:04.543  INFO 3920 --- [  restartedMain] o.s.d.r.w.BasePathAwareHandlerMapping    : Mapped "{[/profile/{repository}],methods=[GET],produces=[application/alps+json || */*]}" onto org.springframework.http.HttpEntity<org.springframework.data.rest.webmvc.RootResourceInformation> org.springframework.data.rest.webmvc.alps.AlpsController.descriptor(org.springframework.data.rest.webmvc.RootResourceInformation)
2018-08-15 15:44:04.544  INFO 3920 --- [  restartedMain] o.s.d.r.w.BasePathAwareHandlerMapping    : Mapped "{[/profile/{repository}],methods=[OPTIONS],produces=[application/alps+json]}" onto org.springframework.http.HttpEntity<?> org.springframework.data.rest.webmvc.alps.AlpsController.alpsOptions()
2018-08-15 15:44:04.544  INFO 3920 --- [  restartedMain] o.s.d.r.w.BasePathAwareHandlerMapping    : Mapped "{[/profile],methods=[GET]}" onto org.springframework.http.HttpEntity<org.springframework.hateoas.ResourceSupport> org.springframework.data.rest.webmvc.ProfileController.listAllFormsOfMetadata()
2018-08-15 15:44:04.544  INFO 3920 --- [  restartedMain] o.s.d.r.w.BasePathAwareHandlerMapping    : Mapped "{[/profile],methods=[OPTIONS]}" onto public org.springframework.http.HttpEntity<?> org.springframework.data.rest.webmvc.ProfileController.profileOptions()
2018-08-15 15:44:04.545  INFO 3920 --- [  restartedMain] o.s.d.r.w.BasePathAwareHandlerMapping    : Mapped "{[/profile/{repository}],methods=[GET],produces=[application/schema+json]}" onto public org.springframework.http.HttpEntity<org.springframework.data.rest.webmvc.json.JsonSchema> org.springframework.data.rest.webmvc.RepositorySchemaController.schema(org.springframework.data.rest.webmvc.RootResourceInformation)
2018-08-15 15:44:04.678  INFO 3920 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2018-08-15 15:44:04.695  INFO 3920 --- [  restartedMain] o.s.b.a.e.web.EndpointLinksResolver      : Exposing 2 endpoint(s) beneath base path '/actuator'
2018-08-15 15:44:04.705  INFO 3920 --- [  restartedMain] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped "{[/actuator/health],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.servlet.AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2018-08-15 15:44:04.706  INFO 3920 --- [  restartedMain] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped "{[/actuator/info],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.web.servlet.AbstractWebMvcEndpointHandlerMapping$OperationHandler.handle(javax.servlet.http.HttpServletRequest,java.util.Map<java.lang.String, java.lang.String>)
2018-08-15 15:44:04.707  INFO 3920 --- [  restartedMain] s.b.a.e.w.s.WebMvcEndpointHandlerMapping : Mapped "{[/actuator],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto protected java.util.Map<java.lang.String, java.util.Map<java.lang.String, org.springframework.boot.actuate.endpoint.web.Link>> org.springframework.boot.actuate.endpoint.web.servlet.WebMvcEndpointHandlerMapping.links(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2018-08-15 15:44:04.831  INFO 3920 --- [  restartedMain] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-08-15 15:44:04.833  INFO 3920 --- [  restartedMain] o.s.j.e.a.AnnotationMBeanExporter        : Bean with name 'dataSource' has been autodetected for JMX exposure
2018-08-15 15:44:04.846  INFO 3920 --- [  restartedMain] o.s.j.e.a.AnnotationMBeanExporter        : Located MBean 'dataSource': registering with JMX server as MBean [com.zaxxer.hikari:name=dataSource,type=HikariDataSource]
2018-08-15 15:44:04.903  INFO 3920 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2018-08-15 15:44:04.907  INFO 3920 --- [  restartedMain] .H.H.HospitalManagementSystemApplication : Started HospitalManagementSystemApplication in 8.729 seconds (JVM running for 10.204)
2018-08-15 15:45:23.324  INFO 3920 --- [nio-8080-exec-2] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring FrameworkServlet 'dispatcherServlet'
2018-08-15 15:45:23.325  INFO 3920 --- [nio-8080-exec-2] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization started
2018-08-15 15:45:23.373  INFO 3920 --- [nio-8080-exec-2] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization completed in 48 ms
2018-08-15 15:45:29.741  INFO 3920 --- [nio-8080-exec-3] o.h.h.i.QueryTranslatorFactoryInitiator  : HHH000397: Using ASTQueryTranslatorFactory
<----------------- Payment List ------------------>  3
com.example.HospitalManagementSystem.HospitalManagementSystem.Model.Payment@77456ddc
com.example.HospitalManagementSystem.HospitalManagementSystem.Model.Payment@4c699830
com.example.HospitalManagementSystem.HospitalManagementSystem.Model.Payment@109e37ec
<----------------- Bill List ------------------>  3
com.example.HospitalManagementSystem.HospitalManagementSystem.Model.Bill@78d63081
com.example.HospitalManagementSystem.HospitalManagementSystem.Model.Bill@759f9952
com.example.HospitalManagementSystem.HospitalManagementSystem.Model.Bill@64e39014

You have no getters and no setters in both Entity classes Bill and Payment.

The JSON serializer looks for these.

If you add getters/setters everything works as expected.