// expect a tuple holding one field - chararray or bytearray
Assert.isTrue(from instanceof SinkCall,
String.format("Unexpected object type, expecting [%s], given [%s]", SinkCall.class, from.getClass()));
// handle common cases
SinkCall sinkCall = (SinkCall) from;
Tuple rawTuple = sinkCall.getOutgoingEntry().getTuple();
if (rawTuple == null || rawTuple.isEmpty()) {
to.bytes("{}");
return;
}