Write ES error with Spark 2.0 release

It seems that you are using version 2.3.3, which only supports up to spark 1.6.1. If you would like to use the Spark 2.0 compatibility, you will need to switch to using the 5.0.0-alpha5 version. Please note that this is an alpha release version and should be used for testing purposes only (i.e. not to be used in production)!!!