docs: protected void incrementBinaryReferenceCount( BinaryKey binaryKey,
                                                    Set<BinaryKey> unusedBinaryKeys,
                                                    Set<BinaryKey> usedBinaryKeys ) {
          // Find the document metadata and increment the usage count ...
          String sha1 = binaryKey.toString();
          String key = keyForBinaryReferenceDocument(sha1);
          // don't acquire a lock since we've already done this at the beginning of the #save
          EditableDocument entry = documentStore.edit(key, false);
          if (entry == null) {
              // The document doesn't yet exist, so create it ...
              Document content = Schematic.newDocument(SHA1, sha1, REFERENCE_COUNT, 1L);
              documentStore.localStore().put(key, content);
          } else {
              Long countValue = entry.getLong(REFERENCE_COUNT);
              entry.setNumber(REFERENCE_COUNT, countValue != null ? countValue + 1 : 1L);
          }
          // We're using the sha1, so remove it if its in the set of unused binary keys ...
          if (unusedBinaryKeys != null) {
              unusedBinaryKeys.remove(binaryKey);
          }
          if (usedBinaryKeys != null) {
              usedBinaryKeys.add(binaryKey);
          }
      }