Custom iOS Framework Not Added to 'Embedded Binaries' Section in Xcode

My Cordova plugin includes a few custom framework binaries. I am trying to add them to the plugin as described here - https://cordova.apache.org/docs/en/latest/plugin_ref/spec.html#framework.

For example:

<framework src="src/ios/frameworks/SalesforceSDKCore.framework" custom="true" />

I then use the Cordova CLI (6.4.0) to generate a Cordova app and add my plugin. The framework is added correctly to the dependencies in the project and is linked correctly as well. As a result, compilation works fine. However, when I run the app, it complains with the following error message:

dyld: Library not loaded: @rpath/SalesforceAnalytics.framework/SalesforceAnalytics
  Referenced from: /Users/bhariharan/Library/Developer/CoreSimulator/Devices/7FE0CFC8-CFFD-432B-A4BF-66E552B7D1A8/data/Containers/Bundle/Application/E2D414CF-541B-4440-9FD1-EA65414DAAA8/Test8.app/Test8
  Reason: image not found

Basically, the issue is that the custom frameworks I added in plugin.xml are not added to the 'Embedded Binaries' section, and I can't seem to find a way to do that via plugin.xml.

A custom framework inclusion should automatically be added to the 'Embedded Binaries' section of the generated app in Xcode.