Add Netflix Hystrix and hystrix.stream endpoint to Spring Boot 2.4.x

HystrixConfig.java

@Configuration
public class HystrixConfig {
    @Bean
    public ServletRegistrationBean<HystrixMetricsStreamServlet> hystrixStreamServlet(){
        return new ServletRegistrationBean<>(new HystrixMetricsStreamServlet(), "/hystrix.stream");
    }
}

pom.xml

    <properties>
        <hystrix.version>1.5.18</hystrix.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>com.netflix.hystrix</groupId>
            <artifactId>hystrix-request-servlet</artifactId>
            <version>${hystrix.version}</version>
        </dependency>
        <dependency>
            <groupId>com.netflix.hystrix</groupId>
            <artifactId>hystrix-metrics-event-stream</artifactId>
            <version>${hystrix.version}</version>
        </dependency>
        <!-- support for rx result types in spring boot -->
        <dependency>
            <groupId>io.reactivex</groupId>
            <artifactId>rxjava-reactive-streams</artifactId>
        </dependency>