I able to to see the additional information on the detail screen, below which is the Request Header and Request Parameter info. I tried capturing just the Client name by creating a new measure with the Header Value, but when i create a Business Transaction to split by newly API Header, I'm getting nothing. I have tried (.*?) as Regular Expression. So Purepath information is coming, so I should be able use that for filtering, correct?
yes, that measure looks fine as far as I can tell. If you don't get any purepaths in your BT, try the same BT without the filter.
(important side note:
If you want to use the built-in "PurePath Response Time" as a filter, it's very much recommended to create a new measure based on it instead of using the built-in one, because any threshold or restriction you might want to set on this measure will affect all purepaths and all BTs, and that's normally not what you want.)
It is not clear to me what are you trying to achieve exactly? AFAI Understand, are you trying to split the purepaths in the BT by 'API Header' in request header/parameters?
If so, you need to put the below regex in the measure Transformation Regex field box of desired metric measure:
and put this measure into the BT split field.