org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘messageSender’

Error while trying to publish a message from spring boot to Google cloud platform pub/sub. I was trying to publish a message to the Google Cloud Platform pub/sub messaging queue. I was getting the following errors while trying to run the application.Please help.

 :: Spring Boot ::                (v2.5.5)

2021-09-24 21:19:58.710  INFO 5204 --- [           main] c.p.g.o.OrderserviceApplication          : Starting OrderserviceApplication using Java 1.8.0_281 on DELL-PC with PID 5204 (D:DownloadsGit Projectsspring-bootorderservicetargetclasses started by User in D:DownloadsGit Projectsspring-bootorderservice)
2021-09-24 21:19:58.714  INFO 5204 --- [           main] c.p.g.o.OrderserviceApplication          : No active profile set, falling back to default profiles: default
2021-09-24 21:20:00.386  INFO 5204 --- [           main] faultConfiguringBeanFactoryPostProcessor : No bean named 'errorChannel' has been explicitly defined. Therefore, a default PublishSubscribeChannel will be created.
2021-09-24 21:20:00.401  INFO 5204 --- [           main] faultConfiguringBeanFactoryPostProcessor : No bean named 'integrationHeaderChannelRegistry' has been explicitly defined. Therefore, a default DefaultHeaderChannelRegistry will be created.
2021-09-24 21:20:00.640  INFO 5204 --- [           main] trationDelegate$BeanPostProcessorChecker : Bean 'org.springframework.integration.config.IntegrationManagementConfiguration' of type [org.springframework.integration.config.IntegrationManagementConfiguration] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2021-09-24 21:20:00.663  INFO 5204 --- [           main] trationDelegate$BeanPostProcessorChecker : Bean 'integrationChannelResolver' of type [org.springframework.integration.support.channel.BeanFactoryChannelResolver] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2021-09-24 21:20:00.666  INFO 5204 --- [           main] trationDelegate$BeanPostProcessorChecker : Bean 'integrationDisposableAutoCreatedBeans' of type [org.springframework.integration.config.annotation.Disposables] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2021-09-24 21:20:01.277  INFO 5204 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2021-09-24 21:20:01.300  INFO 5204 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2021-09-24 21:20:01.300  INFO 5204 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.53]
2021-09-24 21:20:01.547  INFO 5204 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2021-09-24 21:20:01.548  INFO 5204 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 2691 ms
2021-09-24 21:20:01.984  INFO 5204 --- [           main] c.g.c.s.a.c.GcpContextAutoConfiguration  : The default project ID is null
2021-09-24 21:20:02.121  INFO 5204 --- [           main] c.g.c.s.core.DefaultCredentialsProvider  : Default credentials provider for service account [e-mail]
2021-09-24 21:20:02.121  INFO 5204 --- [           main] c.g.c.s.core.DefaultCredentialsProvider  : Scopes in use by default credentials: [https://www.googleapis.com/auth/pubsub, https://www.googleapis.com/auth/spanner.admin, https://www.googleapis.com/auth/spanner.data, https://www.googleapis.com/auth/datastore, https://www.googleapis.com/auth/sqlservice.admin, https://www.googleapis.com/auth/devstorage.read_only, https://www.googleapis.com/auth/devstorage.read_write, https://www.googleapis.com/auth/cloudruntimeconfig, https://www.googleapis.com/auth/trace.append, https://www.googleapis.com/auth/cloud-platform, https://www.googleapis.com/auth/cloud-vision, https://www.googleapis.com/auth/bigquery, https://www.googleapis.com/auth/monitoring.write]
2021-09-24 21:20:02.193  WARN 5204 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'messageSender' defined in com.project.gcp.orderservice.OrderserviceApplication: Unsatisfied dependency expressed through method 'messageSender' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'pubSubTemplate' defined in class path resource [com/google/cloud/spring/autoconfigure/pubsub/GcpPubSubAutoConfiguration.class]: Unsatisfied dependency expressed through method 'pubSubTemplate' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'pubSubPublisherTemplate' defined in class path resource [com/google/cloud/spring/autoconfigure/pubsub/GcpPubSubAutoConfiguration.class]: Unsatisfied dependency expressed through method 'pubSubPublisherTemplate' parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultPublisherFactory' defined in class path resource [com/google/cloud/spring/autoconfigure/pubsub/GcpPubSubAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.google.cloud.spring.pubsub.support.PublisherFactory]: Factory method 'defaultPublisherFactory' threw exception; nested exception is java.lang.IllegalArgumentException: The project ID can't be null or empty.
2021-09-24 21:20:02.213  INFO 5204 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2021-09-24 21:20:02.237  INFO 5204 --- [           main] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2021-09-24 21:20:02.274 ERROR 5204 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'messageSender' defined in com.project.gcp.orderservice.OrderserviceApplication: Unsatisfied dependency expressed through method 'messageSender' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'pubSubTemplate' defined in class path resource [com/google/cloud/spring/autoconfigure/pubsub/GcpPubSubAutoConfiguration.class]: Unsatisfied dependency expressed through method 'pubSubTemplate' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'pubSubPublisherTemplate' defined in class path resource [com/google/cloud/spring/autoconfigure/pubsub/GcpPubSubAutoConfiguration.class]: Unsatisfied dependency expressed through method 'pubSubPublisherTemplate' parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultPublisherFactory' defined in class path resource [com/google/cloud/spring/autoconfigure/pubsub/GcpPubSubAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.google.cloud.spring.pubsub.support.PublisherFactory]: Factory method 'defaultPublisherFactory' threw exception; nested exception is java.lang.IllegalArgumentException: The project ID can't be null or empty.
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:800) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:541) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1352) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1195) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:944) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918) ~[spring-context-5.3.10.jar:5.3.10]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.10.jar:5.3.10]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.5.5.jar:2.5.5]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:754) [spring-boot-2.5.5.jar:2.5.5]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:434) [spring-boot-2.5.5.jar:2.5.5]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:338) [spring-boot-2.5.5.jar:2.5.5]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1343) [spring-boot-2.5.5.jar:2.5.5]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1332) [spring-boot-2.5.5.jar:2.5.5]
    at com.project.gcp.orderservice.OrderserviceApplication.main(OrderserviceApplication.java:27) [classes/:na]
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'pubSubTemplate' defined in class path resource [com/google/cloud/spring/autoconfigure/pubsub/GcpPubSubAutoConfiguration.class]: Unsatisfied dependency expressed through method 'pubSubTemplate' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'pubSubPublisherTemplate' defined in class path resource [com/google/cloud/spring/autoconfigure/pubsub/GcpPubSubAutoConfiguration.class]: Unsatisfied dependency expressed through method 'pubSubPublisherTemplate' parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultPublisherFactory' defined in class path resource [com/google/cloud/spring/autoconfigure/pubsub/GcpPubSubAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.google.cloud.spring.pubsub.support.PublisherFactory]: Factory method 'defaultPublisherFactory' threw exception; nested exception is java.lang.IllegalArgumentException: The project ID can't be null or empty.
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:800) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:541) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1352) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1195) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1380) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1300) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:887) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:791) ~[spring-beans-5.3.10.jar:5.3.10]
    ... 19 common frames omitted
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'pubSubPublisherTemplate' defined in class path resource [com/google/cloud/spring/autoconfigure/pubsub/GcpPubSubAutoConfiguration.class]: Unsatisfied dependency expressed through method 'pubSubPublisherTemplate' parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultPublisherFactory' defined in class path resource [com/google/cloud/spring/autoconfigure/pubsub/GcpPubSubAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.google.cloud.spring.pubsub.support.PublisherFactory]: Factory method 'defaultPublisherFactory' threw exception; nested exception is java.lang.IllegalArgumentException: The project ID can't be null or empty.
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:800) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:541) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1352) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1195) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1380) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1300) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:887) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:791) ~[spring-beans-5.3.10.jar:5.3.10]
    ... 33 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultPublisherFactory' defined in class path resource [com/google/cloud/spring/autoconfigure/pubsub/GcpPubSubAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.google.cloud.spring.pubsub.support.PublisherFactory]: Factory method 'defaultPublisherFactory' threw exception; nested exception is java.lang.IllegalArgumentException: The project ID can't be null or empty.
    at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:658) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:638) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1352) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1195) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1380) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1300) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:887) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:791) ~[spring-beans-5.3.10.jar:5.3.10]
    ... 47 common frames omitted
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.google.cloud.spring.pubsub.support.PublisherFactory]: Factory method 'defaultPublisherFactory' threw exception; nested exception is java.lang.IllegalArgumentException: The project ID can't be null or empty.
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.3.10.jar:5.3.10]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:653) ~[spring-beans-5.3.10.jar:5.3.10]
    ... 61 common frames omitted
Caused by: java.lang.IllegalArgumentException: The project ID can't be null or empty.
    at org.springframework.util.Assert.hasText(Assert.java:289) ~[spring-core-5.3.10.jar:5.3.10]
    at com.google.cloud.spring.pubsub.support.DefaultPublisherFactory.<init>(DefaultPublisherFactory.java:71) ~[spring-cloud-gcp-pubsub-2.0.4.jar:2.0.4]
    at com.google.cloud.spring.autoconfigure.pubsub.GcpPubSubAutoConfiguration.defaultPublisherFactory(GcpPubSubAutoConfiguration.java:306) ~[spring-cloud-gcp-autoconfigure-2.0.4.jar:2.0.4]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_281]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_281]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_281]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_281]
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.3.10.jar:5.3.10]
    ... 62 common frames omitted

I was using only a single Java Class file.

package com.project.gcp.orderservice;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.integration.annotation.MessagingGateway;
import org.springframework.integration.annotation.ServiceActivator;
import org.springframework.messaging.MessageHandler;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;

import com.google.cloud.spring.pubsub.core.PubSubTemplate;
import com.google.cloud.spring.pubsub.integration.outbound.PubSubMessageHandler;

@SpringBootApplication
@RestController
public class OrderserviceApplication {

    private static final String TOPIC = "order";
    
    
    
    public static void main(String[] args) {
        SpringApplication.run(OrderserviceApplication.class, args);
    }
    
    @Bean
    @ServiceActivator(inputChannel = "pubsubOutputChannel")
    public MessageHandler messageSender(PubSubTemplate pubsubTemplate) {
        return new PubSubMessageHandler(pubsubTemplate, TOPIC);
    }
    
    @MessagingGateway(defaultRequestChannel = "pubsubOutputChannel")
    public interface PubsubOutboundGateway{
        void sendToPubsub(String text);
    }
    
    @Autowired
    private PubsubOutboundGateway messagingGateway;
    
    @PostMapping("/publishMessage")
    public String publishMessage() {
        messagingGateway.sendToPubsub("Hello! This is a Publisher message");
        return "Message published successfully";
    }
        
    

}

Thease are my dependencies(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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.5</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.project.gcp</groupId>
    <artifactId>orderservice</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>orderservice</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud-gcp.version>2.0.4</spring-cloud-gcp.version>
        <spring-cloud.version>2020.0.4</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-integration</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.google.cloud</groupId>
            <artifactId>spring-cloud-gcp-starter-pubsub</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.integration</groupId>
            <artifactId>spring-integration-http</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.integration</groupId>
            <artifactId>spring-integration-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>com.google.cloud</groupId>
                <artifactId>spring-cloud-gcp-dependencies</artifactId>
                <version>${spring-cloud-gcp.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

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

</project>

Please help. Thank you.

Answer

I solved this problem. This problem occured due to a smaller error I made in the application.properties file. Instead of spring.cloud.gcp.project-id I used spring.cloud.gcp.project.id.