Is flowregistry attribute of flow-executor necessary or not

[MiB]

What's the practical difference between

<webflow:flow-executor id="flowExecutor" />

without any attributes and tying it to the flowRegistry like

<flow:flow-executor id="flowExecutor" flow-registry="flowRegistry"/>

?

Does the first imply some convention setting making the flowregistry attribute unnecessary? Is the flow-executor still aware of the flowRegistry? By which mechanism?
I noticed this difference between how Spring Roo 1.2m1 sets up projects without any attributes and the examples in the Spring documentation and elsewhere that does spell this out. When is it necessary to have this attribute and when don't you need it?

[MiB]

It seems

 flow-registry="flowRegistry"

is default as a convention value even when not written out. But I don't think this is clear from the documentation. That this value is "default" could mean you just have to write "flow-registry" without any specific value.

So the conclusion seems to be

 flow-registry="flowRegistry"

is always unnecessary unless the id of the flow-registry is something else than "flowRegistry".