in java/dataflow-connector-examples/src/main/java/com/google/cloud/bigtable/dataflow/example/PubsubWordCount.java [79:85]
public void processElement(DoFn<KV<String, Long>, Mutation>.ProcessContext c)
throws Exception {
KV<String, Long> element = c.element();
byte[] key = element.getKey().getBytes();
byte[] count = Bytes.toBytes(element.getValue());
c.output(new Put(key).addColumn(FAMILY, QUALIFIER, count));
}