AsyncLoadExecutor类的mode设值问题

设置``````的时候，由于setMode方法被重载，bean设置的时候出问题
```java
Caused by: java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'com.alibaba.asyncload.AsyncLoadExecutor$HandleMode' for property 'mode': no matching editors or conversion strategy found
```

Start by locating the AsyncLoadExecutor class and its overloaded setMode methods, then reproduce the XML bean configuration using mode="REJECT". Trace how the String value is converted to HandleMode and confirm that the configuration succeeds without the reported IllegalStateException.

Written by the indexing model from the issue text.