IndexingDocjoinerDataVersion

DataVersion tracks the version of data in CompositeDoc. The notion of "data" here is loose and people can define the name of their own. For example, a signal generated by Index Signals or an annotation generated by Goldmine (and other components) can all be considered as data here. Each field in this proto represents the human readable version string and the timestamp of one particular data. We choose to explicitly list out all of the data here for better understanding about which data are tracked. NOTE that human_readable_version is not intended for comparison, use timestamp_micros. In addition, we have an annotation about the field paths of each data. With proto reflection (using google3/net/proto2/util/public/field_path.h), downstream systems can take advantage of this annotation to automatically handle newly introduced data without modifying their code. Please also see the comment of FieldProjector above. There are also some fields in DataInfo that annotate who generates the data, the Index Signals or Goldmine annotator name for the fields already onboarded or being onboarded to FDP. Fields without annotation of signal_names or goldmine_annotator_names are not onboarded. Next ID: 543