DDC-1997: [GH-430] EntityManager connection setter

[doctrinebot]

Jira issue originally created by user @beberlei:

This issue is created automatically through a Github pull request on behalf of albertofem:

Url: #430

Message:

I found myself wanting to set the connection in runtime for an EntityManager. I had to use reflection to achieve that. I would be great to have this setter.

[doctrinebot]

Comment created by @beberlei:

A related Github Pull-Request [GH-430] was closed
#430

[doctrinebot]

Issue was closed with resolution "Won't Fix"

[doctrinebot]

Comment created by @doctrinebot:

A related Github Pull-Request [GH-430] was closed:
doctrine/dbal#430