Provide a securityGroupExists(String name) method similar to the S3 bucketExists() one

[axelfontaine]

Currently checking if a security group exists, one must catch an Exception:

try {
    amazonEC2.describeSecurityGroups(new DescribeSecurityGroupsRequest().withGroupNames(ec2SecurityGroup));
    return; //Success, it already exists.
} catch (AmazonServiceException e) {
    //The security group doesn't exist.
}

Having a dedicated method would make this much better.

[hanshuo-aws]

Since the ec2 client is code generated (s3 client is not though), we in general prefer to create separate utility classes for any high-level logic that does not directly map to an existing service API.
The pull-request linked above looks promising. I will close this issue for now and work on getting that change merged asap.