code: public File getRadiusCAFile() throws GuacamoleException {
          return environment.getProperty(
              RadiusGuacamoleProperties.RADIUS_CA_FILE,
              new File(environment.getGuacamoleHome(), "ca.crt")
          );
      }
docs: Returns the CA file for validating certificates for encrypted
  connections to the RADIUS server, as configured in
  guacamole.properties.
  
  @return
  The file name for the CA file for validating
  RADIUS server certificates
  
  @throws GuacamoleException
  If guacamole.properties cannot be parsed.