protected short[] fetchTileArray(TileMatrix tileMatrix, int row, int column) { long key = tileKey(tileMatrix, row, column); ImageSource tileSource = this.coverageSource.get(key); if (tileSource == null) { tileSource = this.tileFactory.createTileSource(tileMatrix, row, column); this.coverageSource.put(key, tileSource, 1); } short[] tileArray = this.coverageCache.get(tileSource); if (tileArray == null && this.isEnableRetrieval()) { this.coverageRetriever.retrieve(tileSource, null, this); } return tileArray; }