I was working with a Customer today installing docs 2.0 using MS SQL as the backend DB.  After the install when Docs started it was unable to connect to the DB and reported the following error:

[1/13/16 16:15:22:680 CST] 000000de DataSourceCon E   DSRA8040I: Failed to connect to the DataSource.  Encountered "": java.sql.SQLException: Login failed for user 'MSSQL_USER'. ClientConnectionId:4309e2b8-8bcc-4434-ba35-96b1e2c79868 DSRA0010E: SQL State = S0001, Error Code = 18,456

[1/13/16 16:15:22:708 CST] 000000de MBeanHelper   E   Could not invoke an operation on object: WebSphere:name=DataSourceCfgHelper,process=dmgr,platform=dynamicproxy,no de=Connections01DmgrNode,version=8.5.5.4,type=DataSourceCfgHelper,mbeanIdentifier=DataSourceCfgHelper,cell=Connections01Cell,spec=1.0 because of an mbean exception: java.sql.SQLException: Login failed for user 'MSSQL_USER'. ClientConnectionId:4309e2b8-8bcc-4434-ba35-96b1e2c79868 DSRA0010E: SQL State = S0001, Error Code = 18,456

It appears to be an issue just with MS SQL servers, the fix was to do the following in the Integrated Solution Console

resources - jdbc - data sources
select docs, then click on custom properties
set integratedSecurity to true