After additional discussion with rxin, I think having all the possible `TripletField` options is confusing. This pull request reduces the triplet fields to:
```java
/**
* None of the triplet fields are exposed.
*/
public static final TripletFields None = new TripletFields(false, false, false);
/**
* Expose only the edge field and not the source or destination field.
*/
public static final TripletFields EdgeOnly = new TripletFields(false, false, true);
/**
* Expose the source and edge fields but not the destination field. (Same as Src)
*/
public static final TripletFields Src = new TripletFields(true, false, true);
/**
* Expose the destination and edge fields but not the source field. (Same as Dst)
*/
public static final TripletFields Dst = new TripletFields(false, true, true);
/**
* Expose all the fields (source, edge, and destination).
*/
public static final TripletFields All = new TripletFields(true, true, true);
```
Author: Joseph E. Gonzalez <joseph.e.gonzalez@gmail.com>
Closes#3472 from jegonzal/SimplifyTripletFields and squashes the following commits:
91796b5 [Joseph E. Gonzalez] removing confusing triplet fields
288ce583b0