Support Java 8 class files

[GoogleCodeExporter]

Currently the checker prints a warning (or fails the build), if you use Java 8 
to verify your classes. The problem is: It must read class files from rt.jar, 
which are in Java 8 format.

ASM 5.0 is not yet released, but the file format did not change at all (they 
just added new code attributes). So ASM 4.x could read the classes, but it 
checks the version header. The idea here is to patch the class if it is in 
version 52 (Java 8). It would just downgrade the signature to version 51.

The checker would still not support Java 8 "officially", but will not fail to 
work. No signature files for Java 8 will be provided until Java 8 is officially 
released.

Original issue reported on code.google.com by uwe.h.schindler on 27 Apr 2013 at 4:53

[GoogleCodeExporter]

I also added a class file with a test, so forbidden APIs are also detected 
inside the new Java 8 features:
- Default interface methods
- Closures

Original comment by uwe.h.schindler on 27 Apr 2013 at 8:45

• Changed state: Committed

[GoogleCodeExporter]

Original comment by uwe.h.schindler on 28 Apr 2013 at 1:40

• Changed state: Fixed

[GoogleCodeExporter]

The changes were released with version 1.3. It was tested with Oracle Java 8 
preview build 86. If the class format changes again, this no longer applies and 
we may need to further improve this.

Original comment by uwe.h.schindler on 1 May 2013 at 11:36