code: @GetMapping("/mappingproject/{id}")
    public String viewMappingProject(@PathVariable("id") String identifier, Model model) {
      MappingProject project = mappingService.getMappingProject(identifier);
      MappingTarget mappingTarget = project.getMappingTargets().get(0);
      String target = mappingTarget.getName();
      model.addAttribute("entityTypes", getNewSources(mappingTarget));
      model.addAttribute(
          "compatibleTargetEntities",
          mappingService.getCompatibleEntityTypes(mappingTarget.getTarget()).collect(toList()));
      model.addAttribute("selectedTarget", target);
      model.addAttribute("mappingProject", project);
      model.addAttribute("attributeTagMap", getTagsForAttribute(target, project));
      model.addAttribute(
          "packages",
          dataService
              .getMeta()
              .getPackages()
              .stream()
              .filter(p -> !isSystemPackage(p))
              .collect(toList()));
      return VIEW_SINGLE_MAPPING_PROJECT;
    }
docs: Displays a mapping project.
  
  @param identifier identifier of the {@link MappingProject}
  @param model the model
  @return View name for a single mapping project