public static KeyValue create(final DataInput in) throws IOException {
    return create(in.readInt(), in);
  }
Create a KeyValue reading from <code>in</code>
@param in Where to read bytes from. Creates a byte array to hold the KeyValue backing bytes
          copied from the steam.
@return KeyValue created by deserializing from <code>in</code> OR if we find a length of zero,
        we will return null which can be useful marking a stream as done.
@throws IOException if any IO error happen
hbase-common/src/main/java/org/apache/hadoop/hbase/KeyValue.java