@Deprecated
  // Passing InterfaceAudience.Private args FSDataInputStreamWrapper, CacheConfig and Reference.
  // This is fine as the hook is deprecated any way.
  default StoreFileReader postStoreFileReaderOpen(
    ObserverContext<? extends RegionCoprocessorEnvironment> ctx, FileSystem fs, Path p,
    FSDataInputStreamWrapper in, long size, CacheConfig cacheConf, Reference r,
    StoreFileReader reader) throws IOException {
    return reader;
  }
Called after the creation of Reader for a store file.
@param ctx    the environment provided by the region server
@param fs     fileystem to read from
@param p      path to the file
@param in     {@link FSDataInputStreamWrapper}
@param size   Full size of the file
@param r      original reference file. This will be not null only when reading a split file.
@param reader the base reader instance
@return The reader to use
@deprecated For Phoenix only, StoreFileReader is not a stable interface.
hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/RegionObserver.java