docs: public static Map<String, Object> findFreeMarkerContextVariables(Variables variables, String... varNames)
      {
          Map<String, Object> results = new HashMap<>();
  
          for (String varName : varNames)
          {
              WindupVertexFrame payload = null;
              try
              {
                  payload = Iteration.getCurrentPayload(variables, null, varName);
              }
              catch (IllegalStateException | IllegalArgumentException e)
              {
                  // oh well
              }
  
              if (payload != null)
              {
                  results.put(varName, payload);
              }
              else
              {
                  Iterable<? extends WindupVertexFrame> var = variables.findVariable(varName);
                  if (var != null)
                  {
                      results.put(varName, var);
                  }
              }
          }
          return results;
      }