Support for buildpacks in ApplicationManifest builder

[ilayaperumalg]

It looks like the CF Java client doesn't have the support to add buildpacks attribute to the ApplicationManifest via the ApplicationManifest builder as I see only buildpack attribute in there.

Does this support exist in some way already or Is this something yet to be added?

[twoseat]

This has been an outstanding issue for a while, tracked in #921. If you have the urge to provide a PR please go ahead! Otherwise I'm not sure when I can get to it.