@org.apache.thrift.annotation.Nullable
  public java.lang.Object getFieldValue(_Fields field) {
    switch (field) {
    case START_ROW:
      return getStartRow();

    case STOP_ROW:
      return getStopRow();

    case TIMESTAMP:
      return getTimestamp();

    case COLUMNS:
      return getColumns();

    case CACHING:
      return getCaching();

    case FILTER_STRING:
      return getFilterString();

    case BATCH_SIZE:
      return getBatchSize();

    case SORT_COLUMNS:
      return isSortColumns();

    case REVERSED:
      return isReversed();

    case CACHE_BLOCKS:
      return isCacheBlocks();

    }
    throw new java.lang.IllegalStateException();
  }
Returns true if field cacheBlocks is set (has been assigned a value) and false otherwise
hbase-thrift/src/main/java/org/apache/hadoop/hbase/thrift/generated/TScan.java