Updates a DirCache by adding individual DirCacheEntrys. A builder always starts from a clean slate and appends in every single DirCacheEntry which the final updated index must have to reflect its new content. For maximum performance applications should add entries in path name order. Adding entries out of order is permitted, however a final sorting pass will be implicitly performed during finish() to correct any out-of-order entries. Duplicate detection is also delayed until the sorting is complete.