code: private void queueProcessable(final IEngineProcessable processableModel) {
  
          ensurePendingCapacity();
  
          final TemplateFlowController controller = this.flowController;
  
          this.pendingProcessings[this.pendingProcessingsSize] = processableModel;
          this.pendingProcessingsSize++;
  
          if (controller.stopProcessing) {
              controller.processorTemplateHandlerPending = true;
              return;
          }
  
          final boolean processed = this.pendingProcessings[this.pendingProcessingsSize - 1].process();
          if (!processed) {
              controller.processorTemplateHandlerPending = true;
              return;
          }
          this.pendingProcessingsSize--;
  
          controller.processorTemplateHandlerPending = false;
  
      }
docs: /*
  This will be called by any handleX() methods (only when throttling is enabled) whenever they have to execute
  work that might potentially get stopped and therefore be left in the pending queue.