Preparing migrations to inline classes

[Nir Lisker]

Hi,

Project Valhalla is planning to create an annotation to apply to classes
that are planned to be migrated to inline classes [1]. As part of the
migration requirements, classes can't have a public or protected
constructor, and this is the main breaking change. They must also be final,
though I doubt many of these were extended.

We should start compiling a list of classes that are candidates
for migration so we will have enough time to deprecate constructors and
otherwise prepare developers for these changes when inline classes will be
ready.

As an example, Point2D/3D are good migration candidates. They will need to
have their constrictors removed and the classes made final. Other
candidates are:
javafx.css.Size
javafx.geometry.Dimension2D
javafx.geometry.Insets

Internal classes are less of a problem and can be migrated without
preparation.

- Nir

[1] https://openjdk.java.net/jeps/390