referenceAdder(searchSymbol) {
            const symbolId = getSymbolId(searchSymbol);
            let references = this.symbolIdToReferences[symbolId];
            if (!references) {
              references = this.symbolIdToReferences[symbolId] = [];
              this.result.push({ definition: { type: 0 /* Symbol */, symbol: searchSymbol }, references });
            }
            return (node, kind) => references.push(nodeEntry(node, kind));
          }
Callback to add references for a particular searched symbol.
This initializes a reference group, so only call this if you will add at least one reference.