Validation should fail if a dependency is only used for its builder #132
Description
A dependency, like built_value_generator, which provides a builder is ignored by the dependency check. As a result, you may place it in your dependency list without issue.
My expected outcome is that built_value_generator, when used for its builder, would fail validation if it was not lowered to a dev_dependency.
The following packages contain builders that are auto-applied or referenced in "build.yaml"
* built_value_generator