I'm going to try to minimise use of this (as per
https://github.com/google/guice/wiki/Avoid-Injecting-Closable-Resources).
For example, I'm going to inject a pooling DataSource rather than
Connection objects, as per the advice at the end of the page. However,
HikariCP's DataSource implementation is itself Closeable.
Signed-off-by: Graham <gpe@openrs2.org>
