code: @Override
      public String get(Object handle) throws IOException {
          if (!(handle instanceof File)) {
              throw new IllegalArgumentException("Expected File, but was " + handle.getClass());
          }
  
          File eventFile = (File) handle;
          if (eventFile.exists() && eventFile.isFile()) {
              return KeenUtils.convertFileToString(eventFile);
          } else {
              return null;
          }
      }
docs: {@inheritDoc}