in src/main/java/com/spotify/bigtable/mutate/BigtableMutationImpl.java [148:157]
public BigtableMutation write(final String columnFamily, final String columnQualifier,
final ByteString value, final long timestampMicros) {
final Mutation.SetCell.Builder setCell = Mutation.SetCell.newBuilder()
.setFamilyName(columnFamily)
.setColumnQualifier(ByteString.copyFromUtf8(columnQualifier))
.setValue(value)
.setTimestampMicros(timestampMicros);
mutateRowRequest.addMutations(Mutation.newBuilder().setSetCell(setCell));
return this;
}