public boolean isSetCacheDataOnWrite() {
    return org.apache.thrift.EncodingUtils.testBit(__isset_bitfield, __CACHEDATAONWRITE_ISSET_ID);
  }
Returns true if field cacheDataOnWrite is set (has been assigned a value) and false otherwise
hbase-thrift/src/main/java/org/apache/hadoop/hbase/thrift2/generated/TColumnFamilyDescriptor.java