Hi Pravin,
Sorry for not seeing this earlier. We made these changes to jira-core as a part of our efforts to support storing attachments outside of the shared home directory in object stores like Amazon S3. This means we can no longer provide a Java File to attachments. Instead, use the AttachmentManager to access attachment data directly with the AttachmentManager#streamAttachmentContent method.
If you have any more questions, feel free to ask here, or send me a direct message.
Cheers,
Randy
Sr Software Engineer - DC Cross Product