code: public long getLong(@NotNull final String key) throws InvalidSettingException {
          try {
              return Long.parseLong(getString(key));
          } catch (NumberFormatException ex) {
              throw new InvalidSettingException("Could not convert property '" + key + "' to a long.", ex);
          }
      }
docs: Returns a long value from the properties file. If the value was specified
  as a system property or passed in via the -Dprop=value argument - this
  method will return the value from the system properties before the values
  in the contained configuration file.
  
  @param key the key to lookup within the properties file
  @return the property from the properties file
  @throws org.owasp.dependencycheck.utils.InvalidSettingException is thrown
  if there is an error retrieving the setting