In the class org.ejbca.issuechecker.Issue we use the Priority class from Log4j as return value in the getPriority function. The constants Priority.INFO, Priority.WARN ect appears to be deprecated. Replace it with something which is not deprecated.
As stated in the doc: https://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Priority.html
Refrain from using this class directly, use the Level class instead.