imports - Provides a list of model files and directories to load when validating and building the model. Imports are a local dependency: they are not considered part of model package being built, but are required to build the model package.
sources - Provides a list of relative files or directories that contain the models that are considered the source models of the build.
As per https://smithy.io/2.0/guides/smithy-build-json.html#using-smithy-build-json:
We currently generate
imports
.