fix #89 - read and write List instead of Set during ClassImpl serialization

[jasonk000]

this was a backwards-incompatible change previously introduced

[kgibm]

[ERROR] 	private void writeObject(ObjectOutputStream out) throws IOException {
[ERROR] 	                         ^^^^^^^^^^^^^^^^^^
[ERROR] ObjectOutputStream cannot be resolved to a type

[ERROR] 	private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
[ERROR] 	                        ^^^^^^^^^^^^^^^^^
[ERROR] ObjectInputStream cannot be resolved to a type

[kgibm]

I tested the latest patch and it seems to work. I first cleaned the index files, then loaded with MAT 1.15 and then loaded with a build with this patch and it worked. Previously, the same process with vanilla MAT 1.16 failed.

[jasonk000]

Great, I'm doing a bit more testing on my side and then will finalise the PR. Thank you for the quick feedback!

[jasonk000]

I tested

• MAT 1.15 index, MAT 1.16 can open ✅
• MAT 1.16 index, MAT 1.15 can open ✅
• MAT 1.16 index, MAT 1.16 can open ✅

[krumts]

Shall I prepare a new bugfix release (1.16.1) for this one?
I guess the ones who downloaded 1.16.0 already will have a similar issue when upgrading to 1.16.1... the new version was out for less than a month, this should be a smaller impact I guess.

[kgibm]

Given that we don't often create new releases and my guess is this will impact a non-trivial number of users, so I think that would be worth it, thanks Krum!