A properties file containing additional mappings for the context. They key is the class and the value is the symbol
that should be used. This mapping file will be consulted for symbols for context classes before trying the internal
mapping, which only covers a subset of contexts.
To find out which class you need to map create a Logger for the class
io.jenkins.plugins.customizable_header.headers.ContextAwareHeader on level fine. This will print
the list of contexts when loading a page, e.g. Context: hudson.logging.LogRecorder.
The path can be absolute or relative to JENKINS_HOME.