An Integrity Item might contain attachments. Attachments can be extracted to files using a dedicated command:
import com.sodius.mdw.metamodel.integrity.Attachment;
import com.sodius.mdw.metamodel.integrity.io.ExtractAttachmentCommand;
...
com.sodius.mdw.metamodel.integrity.Attachment attachment = ...;
File outputFile = ...;
new ExtractAttachmentCommand(attachment, outputFile).execute();