visitSource of ASM itself does not contain file names
It looks like the source code file name is missing from your .class files (by
this I mean if ASM is applied to itself!).
This is making it extremely difficult (i.e. we'll need to write a custom
workaround) for us to be able to resolve the sources for a given FQN.
Also, it looks like the published source jars contain a double posting of the
actual sources? Very weird, I was looking at the source for SimpleRemapper (in
the commons) and the source was definitely appended to the existing source
(unless Emacs has a bug).
For an example of how we read this information see
https://github.com/ensime/ensime-
server/blob/master/core/src/main/scala/org/ensime/indexer/ClassfileIndexer.scala
#L64