Redis SSL configuration is not clear in case of SpringBoot with lettuce-core - spring-boot

Question

Spring-boot: 2.0.3.RELEASE
lettuce-core: 5.0.4.RELEASE
spring-data-redis: 2.0.8.RELEASE
So first of all my issue is solved I just don't understand why and it bothers me, so some clarification around this is appreciated.
I have this Redis Configuration in one of the micro-service I'm working on:
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import io.lettuce.core.RedisClient;
import io.lettuce.core.RedisURI;
import io.lettuce.core.api.StatefulRedisConnection;
import io.lettuce.core.resource.ClientResources;
import io.lettuce.core.resource.DefaultClientResources;
#Configuration
public class LettuceConfig {
#Bean(destroyMethod = "shutdown")
ClientResources clientResources() {
return DefaultClientResources.create();
}
#Bean(destroyMethod = "shutdown")
RedisClient redisClient(ClientResources clientResources) {
String host = System.getenv("spring_redis_host") != null ? System.getenv("spring_redis_host") : "127.0.0.1";
String port = System.getenv("spring_redis_port") != null ? System.getenv("spring_redis_port") : "6379";
String password = System.getenv("spring_redis_password") != null ? System.getenv("spring_redis_password") : "";
Boolean isLocal = host.equals("127.0.0.1");
RedisURI redisUri = RedisURI.Builder.redis(host).withSsl(!isLocal).withPassword(password).withPort(Integer.parseInt(port))
.build();
return RedisClient.create(clientResources, redisUri);
}
#Bean(destroyMethod = "close")
StatefulRedisConnection<String, String> connection(RedisClient redisClient) {
return redisClient.connect();
}
}
After I added actuator to the project I realized that the service couldn't connect to the remote Redis in AWS and the service throwed the following Exception:
java.io.IOException: Connection reset by peer
After a quick google search most of the answers suggested that the problem is around the SSL connection I have, but I was confused since the RedisURI contains the withSsl function call.
Just out of curiosity I added the following property to my application.properties file, since I'm using property based Redis configuration in the other services and I knew it works.
spring.redis.ssl=true
Now this solved my problem, but I don't understand why this approach is working and the RedisURI version is not.
Could somebody provide me an explanation, who has a clear understanding about the following situation please?
I can share more from the logs if needed. Thank you!