Apparent inconsistency when using the Java SDK to handle S3 buckets

Hello,

The following Java code is meant to get the full name of the first found S3 bucket which name starts with "mys3" and, if none exists, then to create a new one and return its name.

...
AmazonS3 amazonS3 = AmazonS3ClientBuilder.standard().build();
...
this.bucketName = amazonS3.listBuckets().stream().filter(b -> b.getName().startsWith("mys3")).findFirst().orElse(amazonS3.createBucket("mys3" + RANDOM)).getName();
...

it raises the following exception:

com.amazonaws.services.s3.model.AmazonS3Exception: Your previous request to create the named bucket succeeded and you already own it. (Service: Amazon S3; Status Code: 409; Error Code: BucketAlreadyOwnedByYou; Request ID: D8BV5DZVYFE5P9QA; S3 Extended Request ID: 27GbfEzSb0h3/taU5jB2/DM1vu4Te2mM5GdbgudbpkrJUlKmaDpffGXe1iaPTiGxtU4gjVzhSBU=; Proxy: null), S3 Extended Request ID: 27GbfEzSb0h3/taU5jB2DM1vu4Te2mM5GdbgudbpkrJUlKmaDpffGXe1iaPTiGxtU4gjVzhSBU=

Not sure why this exception is raised as nothing seems to be wrong with the code above and googling for a while, I didn't find any pertinent solution. Then, I replaced the code above by the equivalent one, as follows:

...
AmazonS3 amazonS3 = AmazonS3ClientBuilder.standard().build();
Optional<Bucket> optionalBucket = amazonS3.listBuckets().stream().filter(b -> b.getName().startsWith("mys3")).findFirst();
if (optionalBucket.isPresent())
  this.s3BucketName = optionalBucket.get().getName();
else
  this.s3BucketName = amazonS3.createBucket("mys3" + RANDOM).getName();
...

This time everything works as expected and no exception is raised. Then I tried a 3rd version of the code, also equivalent to the first one:

...
AmazonS3 amazonS3 = AmazonS3ClientBuilder.standard().build();
Optional<Bucket> optionalBucket = amazonS3.listBuckets().stream().filter(b -> b.getName().startsWith("mys3")).findFirst();
this.s3BucketName = optionalBucket.isPresent() ? optionalBucket.get().getName() : amazonS3.createBucket("mys3" + RANDOM).getName();
...

It raised the same exception as previously. So, am I right to say that the AWS Java SDK behave inconsistently as it works differently for different version of equivalent Java code ?