docs: public static String getInstrumentationLevelString() {
          if (disabled)
              return null;
          Map modules = moduleRoot.children;
          if (modules == null) {
              return "";
          } else {
              PerfLevelDescriptor[] plds = new PerfLevelDescriptor[modules.size()];
              Iterator values = modules.values().iterator();
              int i = 0;
              while (values.hasNext()) {
                  PmiModule instance = ((ModuleItem) values.next()).getInstance();
                  plds[i++] = new PerfLevelDescriptor(instance.getPath(),
                                  instance.getInstrumentationLevel(),
                                  instance.getModuleID());
              }
              return PmiUtil.getStringFromPerfLevelSpecs(plds);
          }
      }