[closes #222] add API to encode/decode struct inside structs

[lorban]

Beware: this contains changes that might break the API of struct-decoding lambda helpers.

[AbfrmBlr]

StructArrayEncoder.string throws a null pointer for null values

[AbfrmBlr]

java.lang.NullPointerException
at org.terracotta.runnel.encoding.dataholders.StringDataHolder.encodeString(StringDataHolder.java:48)
at org.terracotta.runnel.encoding.dataholders.StringDataHolder.(StringDataHolder.java:33)
at org.terracotta.runnel.encoding.StructArrayEncoder.string(StructArrayEncoder.java:106)
at org.ehcache.clustered.common.internal.messages.ExceptionCodec.encode(ExceptionCodec.java:65)

[lorban]

@AbfrmBlr : this works as designed: runnel does not encode null values so there are some checks preventing them. What you're supposed to do is add a null check yourself and only encode the string when you have a non-null value.

On the decoding side, runnel doesn't care if there was an encoded value or not: if you decode a field that wasn't encoded, you'll get null back.

But now that makes me wonder if runnel should allow encoding null values and simply ignore them, as well as using wrapper types instead of primitives, that might make the API nicer. Could you open a bug for this? I'll track it and do it if we deem it's worth it. Thanks!

[AbfrmBlr]

I have filed an issue #226 and marked it as a question.