public void setFieldValue(_Fields field, @org.apache.thrift.annotation.Nullable java.lang.Object value) {
    switch (field) {
    case START_ROW:
      if (value == null) {
        unsetStartRow();
      } else {
        if (value instanceof byte[]) {
          setStartRow((byte[])value);
        } else {
          setStartRow((java.nio.ByteBuffer)value);
        }
      }
      break;

    case STOP_ROW:
      if (value == null) {
        unsetStopRow();
      } else {
        if (value instanceof byte[]) {
          setStopRow((byte[])value);
        } else {
          setStopRow((java.nio.ByteBuffer)value);
        }
      }
      break;

    case COLUMNS:
      if (value == null) {
        unsetColumns();
      } else {
        setColumns((java.util.List<TColumn>)value);
      }
      break;

    case CACHING:
      if (value == null) {
        unsetCaching();
      } else {
        setCaching((java.lang.Integer)value);
      }
      break;

    case MAX_VERSIONS:
      if (value == null) {
        unsetMaxVersions();
      } else {
        setMaxVersions((java.lang.Integer)value);
      }
      break;

    case TIME_RANGE:
      if (value == null) {
        unsetTimeRange();
      } else {
        setTimeRange((TTimeRange)value);
      }
      break;

    case FILTER_STRING:
      if (value == null) {
        unsetFilterString();
      } else {
        if (value instanceof byte[]) {
          setFilterString((byte[])value);
        } else {
          setFilterString((java.nio.ByteBuffer)value);
        }
      }
      break;

    case BATCH_SIZE:
      if (value == null) {
        unsetBatchSize();
      } else {
        setBatchSize((java.lang.Integer)value);
      }
      break;

    case ATTRIBUTES:
      if (value == null) {
        unsetAttributes();
      } else {
        setAttributes((java.util.Map<java.nio.ByteBuffer,java.nio.ByteBuffer>)value);
      }
      break;

    case AUTHORIZATIONS:
      if (value == null) {
        unsetAuthorizations();
      } else {
        setAuthorizations((TAuthorization)value);
      }
      break;

    case REVERSED:
      if (value == null) {
        unsetReversed();
      } else {
        setReversed((java.lang.Boolean)value);
      }
      break;

    case CACHE_BLOCKS:
      if (value == null) {
        unsetCacheBlocks();
      } else {
        setCacheBlocks((java.lang.Boolean)value);
      }
      break;

    case COL_FAM_TIME_RANGE_MAP:
      if (value == null) {
        unsetColFamTimeRangeMap();
      } else {
        setColFamTimeRangeMap((java.util.Map<java.nio.ByteBuffer,TTimeRange>)value);
      }
      break;

    case READ_TYPE:
      if (value == null) {
        unsetReadType();
      } else {
        setReadType((TReadType)value);
      }
      break;

    case LIMIT:
      if (value == null) {
        unsetLimit();
      } else {
        setLimit((java.lang.Integer)value);
      }
      break;

    case CONSISTENCY:
      if (value == null) {
        unsetConsistency();
      } else {
        setConsistency((TConsistency)value);
      }
      break;

    case TARGET_REPLICA_ID:
      if (value == null) {
        unsetTargetReplicaId();
      } else {
        setTargetReplicaId((java.lang.Integer)value);
      }
      break;

    case FILTER_BYTES:
      if (value == null) {
        unsetFilterBytes();
      } else {
        if (value instanceof byte[]) {
          setFilterBytes((byte[])value);
        } else {
          setFilterBytes((java.nio.ByteBuffer)value);
        }
      }
      break;

    }
  }
Returns true if field filterBytes is set (has been assigned a value) and false otherwise
hbase-thrift/src/main/java/org/apache/hadoop/hbase/thrift2/generated/TScan.java