This
is a very serious issue for the Spark project because a lot
of Spark users build from source. We are going to upgrade
mqtt version for future releases, but this breaks all
current/past releases. In case you are not familiar with
Spark, it is now the most actively developed Big Data open
source project: in the past year alone, there are close to
400 people that have contributed code to the project. Many
applications are being built on top of this and this can
potentially break all of them. I'd also imagine this breaks
other non-Spark projects that depend on mqtt as well.
A
released artifact in a repository should be immutable. Spark
depends on it, other applications depend on it, and
applications that depend on Spark can depend on it. The
transitive closure is pretty large.
Again,
we are going to upgrade the mqtt dependency in Spark, but I
urge you to add the 0.4.0 artifact back. Otherwise we would
have to be extra cautious in the future with respect to any
dependency on mqtt, e.g. removing it from the dependency or
the default build profile, which would cause inconvenience
for our users also.