Hi Sorry if i mistake with mailing list.
After BEAM-102 was solved in FlinkStreamingPipelineTranslator we have code in visitPrimitiveTransform: if (translator == null && applyCanTranslate(transform, node, translator)) { LOG.info(node.getTransform().getClass().toString()); throw new UnsupportedOperationException( "The transform " + transform + " is currently not supported."); } applyStreamingTransform(transform, node, translator); but applyCanTranslate and applyStreamingTransform always require NotNull translator as result if you try use side input in your code then you will cause NPE Maybe Aljoscha Krettek could describe how this code must work? Regards, Alexey Diomin