Fix checkstyle issues to enforce it

Fix checkstyle issues to enforce it

Fix checkstyle issues to enforce it.

Note: I had to replace the calls to MoreExecutors.sameThread() since the
module didn't compile locally. That method [1] is deprecated anyway.

[1]
https://google.github.io/guava/releases/19.0/api/docs/com/google/common/util/concurrent/MoreExecutors.html#sameThreadExecutor()

Change-Id: I4263cadc0748065b20b425d6860fe36569d913b1
Signed-off-by: David Suarez <david.suarez.fuentes@gmail.com>