I did simple java to java transformation with programmatic configuration and it worked well. Now I need to extend it with following use cases, actually all of them depend on MVEL expressions. I found examples with Xml configuration, so solution may look as follows:
<jb:expression property="underlying" execOnElement="__und">
mapper.lookup(__some/_field)
</jb:expression>
But how to do it with programmatic configuration (i.e. using Bean)?