in src/main/java/com/twitter/nodes/TransformNode.java [59:68]
protected Future<Resp> transform(SourceType source) {
Resp resp = transform.apply(source);
if (resp == null && !canEmitNull()) {
TransformNodeNullException exception =
new TransformNodeNullException(this, node, source);
return Future.exception(exception);
}
return Future.value(resp);
}