How to make lower versions of AEM support PDF content search

[QingZhou]

We are using AEM6.5.10
Unable to support PDF content search on 6.5.10, Adobe engineer told me that it is supported on 6.5.21
We cannot upgrade to the latest version because there are many secondary developments
How can I modify the code to enable PDF content search in version 6.5.10?

[aanchal-sikka]

@QingZhou 

Requesting you to please evaluate if following would help 

https://jackrabbit.apache.org/oak/docs/query/pre-extract-text.html