code: public void setSessionProperty(String name, String value)
      {
          requireNonNull(name, "name is null");
          requireNonNull(value, "value is null");
          checkArgument(!name.isEmpty(), "name is empty");
  
          CharsetEncoder charsetEncoder = US_ASCII.newEncoder();
          checkArgument(name.indexOf('=') < 0, "Session property name must not contain '=': %s", name);
          checkArgument(charsetEncoder.canEncode(name), "Session property name is not US_ASCII: %s", name);
          checkArgument(charsetEncoder.canEncode(value), "Session property value is not US_ASCII: %s", value);
  
          sessionProperties.put(name, value);
      }
docs: Adds a session property (experimental).