code: boolean isGMT() {
  
          java.util.TimeZone inner;
  
          if (this.id == null) {
              inner = java.util.TimeZone.getDefault();
          } else {
              inner = this.tz;
          }
  
          return inner.getID().equals("GMT");
  
      }
docs: <p>Liegt die GMT-Zeitzone vor. </p>
  
  @return  {@code true} if this zone is &quot;GMT&quot; else {@code false}