default String preModifyColumnFamilyStoreFileTracker(
    final ObserverContext<MasterCoprocessorEnvironment> ctx, final TableName tableName,
    final byte[] family, String dstSFT) throws IOException {
    return dstSFT;
  }
Called prior to modifying a family's store file tracker. Called as part of modify family store
file tracker RPC call.
@param ctx       the environment to interact with the framework and master
@param tableName the name of the table
@param family    the column family
@param dstSFT    the store file tracker
@return the store file tracker
hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/MasterObserver.java