iasToXsuaaTokenExchange relies on a physical xsuaa binding and not using the xsuaa credentials from the destination service binding

[ptesny]

Describe the bug
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iasToXsuaaTokenExchange relies on a physical xsuaa binding and not using the xsuaa credentials from the destination service binding.
This is a big problem when there is no xsuaa used for user authentication. In this case the iasToXsuaaTokenExchange will always fail.
To Reproduce
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#4731

Expected behavior
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The SAP cloud SDK should only rely on the xsuaa credentials from the destination service
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Impact / Priority

Affected development phase: e.g. Getting Started, Development, Release, Production

Impact: e.g. No Impact, Inconvenience, Impaired, Blocked

Timeline: e.g. Go-Live is in 12 weeks.

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[marikaner]

Hey @ptesny, this is a good point and I think we have missed that. I already implemented that, but we still need to test the whole IAS support end-2-end better to make sure we don't introduce other issues.

[ptesny]

@marikaner ; thx for confirmation; on a side note this is how the SAP Approuter works...if IAS only then SAP Approuter will exchange the ias token to xsuaa (using xssec lib) relying on the xsuaa credentials from the destination service itself.

the token exchange is triggered automatically via the SAP IAS application parameter called:
xsuaa-cross-consumption: true
That means I do not need to make any changes in the application which is using the cloud sdk