Summary
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Apply the sealed class modifer to java.awt.geom.Path2D

Problem
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java.awt.geom.Path2D allows only two direct sub-classes : Path2D.Float and Path2D.Double but this is not as clear as it could be.

Solution
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Use the new sealed class modifier to explicitly list the two allowed sub-classes.
This is safe since there are no public or protected constructors for Path2D.
However the sub-classes will need to be non-sealed since they do allow sub-classing. 

Specification
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java.awt.geom.Path2D 

<pre>
- public abstract class Path2D implements Shape, Cloneable 
+ public abstract sealed class Path2D implements Shape, Cloneable
+     permits Path2D.Double,
+             Path2D.Float   

-     public static class Float extends Path2D implements Serializable 
+     public static non-sealed class Float extends Path2D implements Serializable 

-     public static class Double extends Path2D implements Serializable 
+     public static non-sealed class Double extends Path2D implements Serializable 
</pre>