About Question enthuware.ocpjp.v7.2.1216 :

[The_Nick]

Leading period/dot characters in file name are treated as regular characters in match operations. For example, the "*" glob pattern matches file name ".login". The Files.isHidden method may be used to test whether a file is considered hidden.

In globbing, "." is always considered as a characther right? not only when it's a leading character in a filename, isn't it?

The_Nick.

[admin]

What do you mean by "always"? Do you have a specific case in mind?
-Paul.

[The_Nick]

*.{java,rtf}
Here for example "." it's not leading but it's in the second position.
The_Nick.

[admin]

Try it out See if *.{java,rtf} matches some file named filejava