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