code: protected Map<String,Object> getPostScriptBindings(Object response) throws ActivityException {
          Map<String,Object> binding = new HashMap<String,Object>();
          String varname = this.getAttributeValue(RESPONSE_VARIABLE);
          if (varname != null && response instanceof String) {
              binding.put("response", getVariableValue(varname));
          }
          else {
              binding.put("response", response);
          }
  
          return binding;
      }
docs: Extra bindings for post-script beyond process variable values.