JDK 10 RFR of JDK-8191839: ModuleElement.DirectiveVisitor :: visit​() method behavior is deviating from the spec.

[Joseph D. Darcy]

Hello,

Please review the doc-only changes for

         JDK-8191839: ModuleElement.DirectiveVisitor :: visit​() method 
behavior is deviating from the spec.
     http://cr.openjdk.java.net/~darcy/8191839.0/

In brief, the bug observes an inconsistency between the @implSpec tag 
and the mainline requirements for one of the default method in 
DirectiveVisitor. After doing a few greps over the javax.lang.model 
code, I found a case of a missing @implSpec tag for a default method and 
change the wording of a few @implSpec tags to be more consistent with 
the conventions in the rest of the API.

Thanks,

-Joe