extract change feed response body lambda to class
extract change feed response body lambda to class

and add a comment, to avoid the same segfault mistake happening again in
the future

nla/outbackcdx,nla/outbackcdx,nla/tinycdxserver,nla/outbackcdx,nla/tinycdxserver,nla/tinycdxserver,nla/tinycdxserver,nla/outbackcdx