This indicates an attack attempt to exploit an Information Disclosure Vulnerability in Apache Druid.
The vulnerability is due to an error in the vulnerable application when handling a maliciously crafted request. A remote attacker may be able exploit this to disclose arbitrary files within the context of the application, via a crafted request.
Apache Druid prior to 0.22
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
Apply the most recent upgrade or patch from the vendor: https://druid.apache.org/