JIRA 7.6 - Get File-Object for Attachment

I need the file object of a specific Attachment…I got the attachment object and I’m wondering how I should get the file as a object…

https://docs.atlassian.com/software/jira/docs/api/7.1.0/com/atlassian/jira/issue/attachment/AttachmentStore.html

https://docs.atlassian.com/software/jira/docs/api/7.1.0/com/atlassian/jira/util/AttachmentUtils.html

https://docs.atlassian.com/software/jira/docs/api/7.6.1/index.html?com/atlassian/jira/issue/AttachmentManager.html

Every Attachment-Class is deprecated or dont even have a Function to get the file object. So whats the secret?

regards.