While configuring the XA data source  in  wildfly User interface ( its  oracle XA data source) console we are facing the failed connection  error .

Later we figured  it out that we  need to add the  line 

<xa-datasource-class>oracle.jdbc.xa.client.OracleXADataSource</xa-datasource-class> in standalone.xml file  of instance  of  wildfly server.

Is  this to be added manually every time  we configure the data sources on wildfly 11.0.0 ?

Is  this  because wildfly  version issue ?

Why standalone.xml file not picking  from the console UI  from the  tab specify driver of  step  (2/4 data source class)