docs: @SuppressWarnings({ "PMD.GuardLogStatement", "PMD.AvoidDuplicateLiterals" })
      public void add(Object obj) {
          synchronized (this) {
              running += 1;
              if (generators != null) {
                  generators.put(obj, null);
                  generatorTracking.finest(() -> "Added generator " + obj
                      + ", " + generators.size() + " generators registered: "
                      + generators.keySet());
              }
              if (running == 1) { // NOPMD, no, not using a constant for this.
                  keepAlive = new Thread("GeneratorRegistry") {
                      @Override
                      public void run() {
                          try {
                              while (true) {
                                  Thread.sleep(Long.MAX_VALUE);
                              }
                          } catch (InterruptedException e) {
                              // Okay, then stop
                          }
                      }
                  };
                  keepAlive.start();
              }
          }
      }