Java – how do you share a low-level utility class between packages without exposing it to a public API?

I have a library project. I want to restrict the public API, but I also have some low-level utility classes that are shared among some packages I need these utility classes to be publicly accessible, but I don't want to expose them in the public API of the library

I'd like to reflect, but this app looks a little messy

Any help will be greatly appreciated

Solution

Do not include these classes in the API documentation or record them with bold warnings: these classes are for internal use only and may be changed or deleted in future API versions Don't use it

Put these classes on COM foo. bar. The internal package is also useful