protected final void checkTimestamp(long ts) {
    Preconditions.checkArgument(ts >= 0, "Timestamp cannot be negative. ts=%s", ts);
  }
@param row Row to check
@throws IllegalArgumentException Thrown if <code>row</code> is empty or null or &gt;
                                 {@link HConstants#MAX_ROW_LENGTH}
@return <code>row</code>
hbase-client/src/main/java/org/apache/hadoop/hbase/client/Mutation.java