@Override
  public long modifyTable(final TableName tableName, final TableDescriptor newDescriptor,
    final long nonceGroup, final long nonce, final boolean reopenRegions) throws IOException {
    checkInitialized();
    return modifyTable(tableName, new TableDescriptorGetter() {
      @Override
      public TableDescriptor get() throws IOException {
        return newDescriptor;
      }
    }, nonceGroup, nonce, false, reopenRegions);

  }
Implement to return TableDescriptor after pre-checks
hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java