com.cloudera.flume.reporter.ReportEvent.hierarchicalMerge()
This method "hierarchically" merges the attributes of another event prefixing each attribute with the specified prefix. So if our current event has attributes (a,b,c), and the one being merged in has attributes (d,e,f), and we have prefix be x, the result event will have attributes (a,b,c, x.d, x.e, x.f) This can be recursive, so if if d was actually an event with (h,i,j) and prefix in that call is y, we could end up with (a,b,c,x.d,x.e, x.f, x.y.h, x.y.i, x.y.j)