public String getFileSystemId() {
        return this.fileSystemId;
    }
<p>
(Optional) If you provide a <code>FileSystemId</code>, EFS returns all access points for that file system;
mutually exclusive with <code>AccessPointId</code>.
</p>

@return (Optional) If you provide a <code>FileSystemId</code>, EFS returns all access points for that file
        system; mutually exclusive with <code>AccessPointId</code>.
aws-java-sdk-efs/src/main/java/com/amazonaws/services/elasticfilesystem/model/DescribeAccessPointsRequest.java