Missing Alias Annotation on Class KafkaSimpleJsonExtractor

Class, KafkaSimpleJsonExtractor, cannot be used because it is not referenced directly by any getExtractor(). Nor can it be used by class, UniversalKafkaSource, because that class has two requirements for dynamically loaded extractor classes: they must extend class, KafkaExtractor, and they must have an "Alias" annotation. KafkaSimpleJsonExtractor lacks the required "Alias" annotation.

The change would add two lines to KafkaSimpleJsonExtractor.java: an import and annotation.