In-compatible type exception when build method return super type

[agavrilov76]

Fix issue #761

[cowtowncoder]

Thanks! Sounds correct to me -- I'll re-read the code later today, but I assume you are absolutely correct here. So after reading, I'd be happy to merge this patch and backport in 2.5.

Just one practicality first: if we haven't yet asked for the Contributor License Agreement (CLA):

https://github.com/FasterXML/jackson/blob/master/contributor-agreement.pdf

we would need a copy (print, fill-in & sign, scan, email to info at fasterxml dot com). One copy is needed and then we can accept all patches for all Jackson projects. Apologies for this, but it is one part of process we need, to keep corporate users (or more like their legal depts :) ) happy.

Thank you again for the contribution!

[agavrilov76]

I've sent the signed contributor agreement to 'info'.

[cowtowncoder]

Ok, I think this is close to correct. I do think that check has to be actually both ways, since it should be legal for builder to also specify it builds a more specific type (original test), as well as less specific (code after change). I'll modify it after merging to ensure both are legal.

Thank you again!