Grouping queries

Hi dear Vert.x team. I recently notice this "group" method feature which seems super promising.

```
public interface SqlClientInternal extends SqlClient {

...
/**
* Experimental API not yet exposed.
*
*

Execute the code {@code block} with a client that defers the flush of queries after its execution.
*
* @param block the block to execute
*/
void group(Handler block);

}

```
I tested it and seems it works pretty good, so I have some questions.

1) Is there approximately plans when this feature will become public feature?
2) Even being internal feature is it already considered fully working (but at out own risk) or it is just at beginning steps?

3) I noticed that this method is fully implemented in SqlClientBase class, but inside CloseablePool it is actually NO-OP

```
@Override
public void group(Handler block) {

}

```
is it by design or it is kinda TODO? Also should not it throw some UnsupportedOperationException becuase at first when I was trying to run on pool I actually got stucked futures and only then I noticed that it is NO-OP.

I will be very grateful for your answers.