This indicates an attack attempt to exploit an Information Disclosure Vulnerability in Atlassian Jira Server.
The vulnerability is due to an error in the vulnerable application when handling a maliciously request. An unauthenticated attacker can exploit this to disclose arbitrary files on the affected machine via a crafted request.
Atlassian Jira Server before version 7.13.2
Atlassian Jira Server from version 8.0.0 and before version 8.02
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
Apply the most recent upgrade or patch from the vendor.