grib/src/main/java/ucar/nc2/grib/collection/GribCollectionImmutable.java
public Coordinate getCoordinate(int index) {
      int grpIndex = coordIndex.get(index);
      return group.coords.get(grpIndex);
    }
public Coordinate getCoordinate(int index) {
      int grpIndex = coordIndex.get(index);
      return group.coords.get(grpIndex);
    }
get the ith coordinate