Spring Boot not loading @ConfigurationProperties

I am developing a Spring boot application where I am trying to configure custom properties for a bean which gives the suppourted extensions for my file .
When I run the application it runs sucessfully with 0 errors but the extensions are not loaded from the application.properties file.

Here is my code in application.properties :-----

suppourted.extensions[0]="jpg"
suppourted.extensions[1]="pdf"
suppourted.extensions[2]="png"

Here is the code of the bean:--

package com.MyBoot.FirstBoot;

import java.util.ArrayList;
import java.util.List;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;


@ConfigurationProperties(prefix = "suppourted")
public class SuppourtedFiles {
	
	private List<String> extensions=new ArrayList<>();

	public List<String>getExtensions() {
		return extensions;
	}

	public void setExtensions(List<String>extensions) {
		this.extensions = extensions;
	}

	@Override
	public String toString() {
		return "SuppourtedFiles [extensions=" + extensions.size() + "]";
	}

}

My main SpringBootApplication:----

package com.MyBoot.FirstBoot;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class FirstBoot1Application {

	public static void main(String[] args) {
		SpringApplication.run(FirstBoot1Application.class, args);
	}
}

I do not understand where the problem is occuring. Kindly help me.

Update:--

I want to send that object to my jsp page for displaying it using model not just create that bean in CommandLineRunner

If I remember correctly you should either use

@Configuration

in your SuppourtedFiles class or

@EnableConfigurationProperties(SuppourtedFiles.class)

in your FirstBoot1Application.

Hope below will work,

Applications:

package com.MyBoot.FirstBoot;

import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;


@SpringBootApplication
@EnableConfigurationProperties(SuppourtedFiles.class)
public class FirstBoot1Application implements CommandLineRunner {
    private final SuppourtedFiles suppourtedFiles;

    public FirstBoot1Application(SuppourtedFiles suppourtedFiles) {
        this.suppourtedFiles = suppourtedFiles;
    }

    @Override
    public void run(String... args) throws Exception {
        System.out.println(suppourtedFiles);
    }

    public static void main(String[] args) {
        SpringApplication.run(FirstBoot1Application.class, args);
    }

}

Configuration Class:

package com.MyBoot.FirstBoot;

import org.springframework.boot.context.properties.ConfigurationProperties;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;


@ConfigurationProperties(prefix = "suppourted")
public class SuppourtedFiles {

    private List<String> extensions = new ArrayList<>();

    public List<String> getExtensions() {
        return extensions;
    }

    public void setExtensions(List<String> extensions) {
        this.extensions = extensions;
    }

    @Override
    public String toString() {
        return "com.MyBoot.FirstBoot.SuppourtedFiles [extensions=" + Arrays.toString(extensions.toArray()) + "]"; // Changed to check if array is filled from spring or not.
    }

}

minimum maven dependencies

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

Optional Dependency for annotation processor:

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-configuration-processor</artifactId>
  <optional>true</optional>
</dependency>

> Please make sure your project packaging is jar or war

Controller:

@RestController
public class SampleController {
    private final SuppourtedFiles suppourtedFiles;

    public SampleController(SuppourtedFiles suppourtedFiles) {
        this.suppourtedFiles = suppourtedFiles;
    }

    @GetMapping("/extensions")
    public ResponseEntity<List<String>> extensions(){
        return ResponseEntity.ok(suppourtedFiles.getExtensions());
    }
}

Controller Dependency:

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

You should have the @Configuration on the SuppourtedFiles class and also the @EnableConfigurationProperties on the FirstBoot1Application class and add the org.springframework.boot:spring-boot-configuration-processor dependency.

package com.MyBoot.FirstBoot;

import java.util.ArrayList;
import java.util.List;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;

@Configuration
@ConfigurationProperties(prefix = "suppourted")
public class SuppourtedFiles {
    //You should not create the extensions object just declare it
    private List<String> extensions;

    public List<String>getExtensions() {
        return extensions;
    }
    public void setExtensions(List<String>extensions) {
        this.extensions = extensions;
    }
}

package com.MyBoot.FirstBoot;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@EnableConfigurationProperties
public class FirstBoot1Application {

    public static void main(String[] args) {
        SpringApplication.run(FirstBoot1Application.class, args);
    }

}

And also in the properties you do not need double quotes. You can just have,

suppourted.extensions[0]=jpg
suppourted.extensions[1]=pdf
suppourted.extensions[2]=png