I remarked that this new function only work with .java 
file but not with .class, even if I mount the javadoc of 
these .class.
For me, I find that a little annoying.
If I have only external API (without source) and the 
Javadoc of the API, I can't be helped by this function. 
And it's a little disappointing.

Svata answer me the following:

"I think that's because the Editor uses Java Hierarchy 
APIs to get the javadoc text. The current implementation 
is able to extract the javadoc from /** */ comments in the 
source, but Clazz module (which implements the API 
for .class files) is not so sophisticated, so it just 
returns "no javadoc". Again, a feature request would 
remind us to see to that Clazz and Javadoc modules 
integrate and cooperate :-)"

So here is the enhancement request