[OpenJDK 2D-Dev] [9] Review Request: 8066132 BufferedImage::getPropertyNames() always returns null

[Sergey Bylokhov]

Hello.
Please review a fix for jdk 9.
BufferedImage::getPropertyNames() was implemented according to 
specification.
Notes:
- The properties map in the constructor is defined as <?,?>, which means 
it can have non-String keys. Long time ago (in 2004) it was defined as 
<String, ?> but was changed to <?,?> in some of (5054615, 5056707, 
5060820, 5061476, 5073707). I am not sure, it is safe to change it back 
to <String,?> or not, so I decided to filter out non-String keys.
  - Unused isAlphaPremultiplied field was removed.

Bug: https://bugs.openjdk.java.net/browse/JDK-8066132
Webrev can be found at: http://cr.openjdk.java.net/~serb/8066132/webrev.00

-- 
Best regards, Sergey.