text: public BytesRef add(BytesRef prefix, BytesRef output) {assert prefix != null;assert output != null;if (prefix == NO_OUTPUT) {return output;} else if (output == NO_OUTPUT) {return prefix;} else {assert prefix.length > 0;assert output.length > 0;BytesRef result = new BytesRef(prefix.length + output.length);System.arraycopy(prefix.bytes, prefix.offset, result.bytes, 0, prefix.length);System.arraycopy(output.bytes, output.offset, result.bytes, prefix.length, output.length);result.length = prefix.length + output.length;return result;}}