The javadoc Standard Doclet has been moving away from the use of frames to navigate around the documentation to the use of javadoc Search.
In recent releases, we have been through a sequence of steps:
1. Frames, no Search (up to JDK 8)
2. Frames generated by not displayed by default
3. Frames not generated by default
Now, the final step is to remove all support for frames in the generated documentation.
This will also mean removing the `--frames` option. The `--no-frames` option will be retained but will effectively become a no-op.