AWS SNS sending with Spring Cloud. Trying to understand

Question

I am newbie in Spring. I am trying to learn it through practice with implementing simple push server for my iOS app with documentation and their samples on GitHub. But I do something wrong and I cannot understand what. Could somebody help me, please?

So my SnsSenderController code is:

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.aws.messaging.core.NotificationMessagingTemplate;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.*;

@RestController                
@RequestMapping("/sns")        
public class SnsSenderController {      

    private static final Logger theLogger = LoggerFactory.getLogger(SnsSenderController.class);
    private final NotificationMessagingTemplate notificationMessagingTemplate;

    @Autowired
    public SnsSenderController(NotificationMessagingTemplate notificationMessagingTemplate) {
        this.notificationMessagingTemplate = notificationMessagingTemplate;
    }

    @RequestMapping(value = "/send", method = RequestMethod.POST)
    @ResponseStatus(HttpStatus.OK)
    public void sendNotification(@RequestBody SnsNotification notification) {
        theLogger.debug("Going to send notification {}", notification);

        this.notificationMessagingTemplate.sendNotification("SnsTopic", notification.getMessage(), notification.getSubject());
    }

}

My SnsNotification class:

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;

public class SnsNotification {

    private final String subject;
    private final String message;

    @JsonCreator
    public SnsNotification(@JsonProperty("subject") String subject, @JsonProperty("message") String message) {
        this.subject = subject;
        this.message = message;
    }

    public String getSubject() {
        return this.subject;
    }

    public String getMessage() {
        return this.message;
    }

    @Override
    public String toString() {
        return "SnsNotification{" + "subject='" + this.subject + '\'' + ", message='" + this.message + '\'' + '}';
    }

}

Beans:

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aws-context="http://www.springframework.org/schema/cloud/aws/context"
       xmlns:aws-messaging="http://www.springframework.org/schema/cloud/aws/messaging"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                           http://www.springframework.org/schema/beans/spring-beans.xsd
                           http://www.springframework.org/schema/cloud/aws/context
                           http://www.springframework.org/schema/cloud/aws/context/spring-cloud-aws-context-1.0.xsd
                           http://www.springframework.org/schema/cloud/aws/messaging
                           http://www.springframework.org/schema/cloud/aws/messaging/spring-cloud-aws-messaging-1.0.xsd">

       <!-- Define global credentials for all the AWS clients -->
       <aws-context:context-credentials>
              <aws-context:instance-profile-credentials/>
              <aws-context:simple-credentials access-key="${accessKey}"
                                              secret-key="${secretKey}"/>
       </aws-context:context-credentials>

       <!-- Messaging-->
       <aws-messaging:notification-messaging-template id="notificationMessagingTemplate" />

</beans>

The main app code is:

import com.amazonaws.services.sns.AmazonSNS;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.aws.core.env.ResourceIdResolver;
import org.springframework.cloud.aws.messaging.core.NotificationMessagingTemplate;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@ComponentScan
@EnableAutoConfiguration

public class MySenderApplication {

    public static void main(String[] args) {
        SpringApplication.run(MySenderApplication.class, args);
    }

    @Bean
    public NotificationMessagingTemplate notificationMessagingTemplate(AmazonSNS amazonSNS, ResourceIdResolver resourceIdResolver) {
        return new NotificationMessagingTemplate(amazonSNS, resourceIdResolver);
    }
}

And it is crash by start with a lot of errors. Please!

UPDATE:

I don't know why, but it starts work... Then two more questions.

1. According to Spring Cloud Docs the connection settings to AWS should be in application.properties. I put it there with keys cloud.aws.credentials.accessKey and cloud.aws.credentials.secretKey but there is an error there: "Cannot resolve configuration property". Why so? What did I miss?
2. According to Spring Docs I can make "notificationMessagingTemplate" there instead of annotation @Bean, but my code works only with @Bean annotation in code. Why so?