code: public static int getNumberOfDependentLayers(String imageContent) throws IOException {
          JsonNode history = Utils.mapper().readTree(imageContent).get("history");
          if (history == null) {
              throw new IllegalStateException("Could not find 'history' tag");
          }
  
          int layersNum = history.size();
          boolean newImageLayers = true;
          for (int i = history.size() - 1; i >= 0; i--) {
  
              if (newImageLayers) {
                  layersNum--;
              }
  
              JsonNode layer = history.get(i);
              JsonNode emptyLayer = layer.get("empty_layer");
              if (!newImageLayers && emptyLayer != null) {
                  layersNum--;
              }
  
              if (layer.get("created_by") == null) {
                  continue;
              }
              String createdBy = layer.get("created_by").textValue();
              if (createdBy.contains("ENTRYPOINT") || createdBy.contains("MAINTAINER")) {
                  newImageLayers = false;
              }
          }
          return layersNum;
      }
docs: Returns number of dependencies layers in the image.
  
  @param imageContent
  @return
  @throws IOException