How to solve "java.io.FileNotFoundException: class path resource cannot be resolved to URL" when trying to add ssl certificate?

Question

I am trying to add an existing SSL certificate(.cer) to a Spring boot application. Followed the following steps,

Step 1: Converted the existing .cer certificate to .p12 certificate using the below command in keytool of JDK 8.

keytool -import -alias cert -file myCertificate.crt -keystore certificate.p12 -storepass password

Step 2 : Placed this certificate.p12 that was generated in "resources" folder of the application.

Step 3 : Added the below configuration in "application.properties"

server.ssl.key-store = classpath:certificate.p12
server.ssl.key-store-password=password
server.ssl.key-store-type=pkcs12
server.ssl.key-alias=cert
server.ssl.key-password=password
server.ssl.enabled=true
server.port=8443  
security.require-ssl=true

Step 4 : Added the below "SecurityConfig.java" file in application.

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.requiresChannel().anyRequest().requiresSecure();
    }
}

Step 5 : Added the below code in "Application.java"

@Bean
    public ServletWebServerFactory servletContainer() {
        TomcatServletWebServerFactory tomcat = new TomcatServletWebServerFactory() {
            @Override
            protected void postProcessContext(Context context) {
                SecurityConstraint securityConstraint = new SecurityConstraint();
                securityConstraint.setUserConstraint("CONFIDENTIAL");
                SecurityCollection collection = new SecurityCollection();
                collection.addPattern("/*");
                securityConstraint.addCollection(collection);
                context.addConstraint(securityConstraint);
            }
        };
        tomcat.addAdditionalTomcatConnectors(redirectConnector());
        return tomcat;
    }
private Connector redirectConnector() {
        Connector connector = new Connector(TomcatServletWebServerFactory.DEFAULT_PROTOCOL);
        connector.setScheme("http");
        connector.setPort(80);
        connector.setSecure(false);
        connector.setRedirectPort(443);
        return connector;
    }

After adding all the above code and configuration changes. I am getting the below exception when I start the spring boot application - Caused by: org.springframework.boot.web.server.WebServerException: Could not load key store 'classpath:certificate.p12' Caused by: java.io.FileNotFoundException: class path resource [certificate.p12] cannot be resolved to URL because it does not exist. Kindly help to fix this issue. Thanks in advance!