Hello @Shruthi B.
As per google, this application is built on Java. Hence, you can follow the the instructions from the following link.
You can make sampling more granual, if interesting methods are really fast thay can be missed if this is only single instance of transaction. I rather suggest making sampling and repeat transactions couple of times (the same one).
To capture PurePaths in general you should know entry points for transactions, even not only interesting methods that are inside them. Maybe you should start digging from methods that are root for all transactions, like doFilter on most Java Applications. Instrumenting them should help. The question is as well how did you create agent group? Did you use wizard or make it manual? I'm asking because maybe adding some default sensor packs will help with purepath visibility.
I tested this long time back but could not capture any purepaths, in fact it will not work. See https://community.apigee.com/articles/37595/apm-integration-with-apigee.html "We often time hear from customers asking for class/method names so that they can instrument Apigee like any home grown java application. This won’t work and is not supported. "