code: protected static synchronized long nextGlobalId() {
      long newIdentifier = System.nanoTime();
  
      while (newIdentifier <= currentIdentifier) {
        newIdentifier = System.nanoTime();
      }
  
      currentIdentifier = newIdentifier;
  
      return newIdentifier;
    }
docs: Generates the next unique identifier (ID) in sequence in a global context, across all instances of this class
  in the same JVM (or rather, {@link ClassLoader}).
  
  @return the next globally unique {@link Long} identifier (ID) in the sequence.
  @see java.lang.System#nanoTime()