@Override
  protected void serialize(ByteBuffer byteBuffer) {
    ReadWriteIOUtils.write(functionName, byteBuffer);
    ReadWriteIOUtils.writeStringList(functionAttributesKeyValueList, byteBuffer);
    ReadWriteIOUtils.write(expressions.size(), byteBuffer);
    for (ViewExpression expression : expressions) {
      ViewExpression.serialize(expression, byteBuffer);
    }
  }
example: select udf(a, b, udf(c)) from root.sg.d;

<p>3 expressions [root.sg.d.a, root.sg.d.b, udf(root.sg.d.c)] will be in this field.
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/schema/view/viewExpression/multi/FunctionViewExpression.java