code: public void addShardedLinkValue(String ownerObjID, FieldDefinition linkDef, String targetObjID, int targetShardNo) {
          assert linkDef.isSharded();
          assert targetShardNo > 0;
          addColumn(SpiderService.termsStoreName(linkDef.getTableDef()),
                    SpiderService.shardedLinkTermRowKey(linkDef, ownerObjID, targetShardNo),
                    targetObjID);
      }
docs: Add a link value column on behalf of the given owner object, referencing the given
  target object ID. This is used when a link is sharded and the owner's shard number
  is > 0. The link value column is added to a special term record.
  
  @param ownerObjID    Object ID of object owns the link field.
  @param linkDef       {@link FieldDefinition} of the link field.
  @param targetObjID   Referenced (target) object ID (owning table is sharded).
  @param targetShardNo Shard number of the target object. Must be > 0.