Appending arrays isn't supported about config

[havocp]

I expect it's because your version is too old, this was added in 0.4.0. Note that akka 2.0.x has an internal cut-and-paste copy of the config lib which does not support +=, therefore you can never use += with akka 2.0.x on your classpath.

[andyscott]

Aah you're totally right. How can I use 0.4.0 with akka 2.0 on my classpath? Just ensure that 0.4.0 has precedence? Or will that break akka 2.0 (I'm trying this now).

[andyscott]

It might be worth documenting this on the readme page.

[havocp]

I did try to mention this in a couple places in the docs (search for "akka" in README and/or HOCON.md) but I can try to improve it.

I'm not sure how to convince the JVM to load 0.4.0 classes; maybe if 0.4.0 is before the akka jar on the classpath? 0.4.0 should be ABI-compatible with what's in Akka, the issue is that it is not serialization-compatible. But the serialization thing would only matter if your environment has 0.4.0 and the akka version talking to each other over remoting.

Worst case you could rebuild Akka from source after pasting in 0.4.0 of course.