code: public boolean isOptOut() {
          synchronized (optOutLock) {
              try {
                  // Reload the metrics file
                  properties.load(new FileInputStream(configurationFile));
              } catch (IOException ex) {
                  if (debug) {
                      System.out.println("[Metrics] " + ex.getMessage());
                  }
                  return true;
              }
  
              return Boolean.parseBoolean(properties.getProperty("opt-out"));
          }
      }
docs: Has the server owner denied plugin metrics?
  
  @return true if metrics should be opted out of it