@Override
        public Message call(EndpointObserver observer) throws IOException {
          return observer.preEndpointInvocation(this, service, methodName, getResult());
        }
@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
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionCoprocessorHost.java