StringBuffer is a legacy synchronized class. StringBuilder is a direct replacement to StringBuffer which generally have better performance.

It means that separate File.exists() check before File.isDirectory() check is redundant.

This is a follow-up commit on @07af5d41:
Inside org.aspectj.apache.bcel.util.ClassPath.getClassPath(), some JVM
version matching occurs which previously did not include Java 16 (I also
added 17-19 to the regex matcher). This fixes test errors like:

java.lang.ClassCastException:
  class org.aspectj.weaver.MissingResolvedTypeWithKnownSignature
  cannot be cast to class
  org.aspectj.weaver.ReferenceType
  (org.aspectj.weaver.MissingResolvedTypeWithKnownSignature and
  org.aspectj.weaver.ReferenceType are in unnamed module
  of loader 'app')

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

Inside org.aspectj.apache.bcel.util.ClassPath.getClassPath(), some JVM
version matching occurs which previously did not include Java 15.
Technically, AspectJ 1.9.6 does not support Java 15, but on GitHub
Actions there is a build job running on a JVM 15. This change should at
least make the weaver tests pass, making that test job more meaningful.

This fixes test errors like

java.lang.ClassCastException:
  class org.aspectj.weaver.MissingResolvedTypeWithKnownSignature
  cannot be cast to class
  org.aspectj.weaver.ReferenceType
  (org.aspectj.weaver.MissingResolvedTypeWithKnownSignature and
  org.aspectj.weaver.ReferenceType are in unnamed module
  of loader 'app')

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>

Reports on declarations of Collection variables made by using the collection class as the type, rather than an appropriate interface.

Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>

Signed-off-by: Lars Grefer <eclipse@larsgrefer.de>

The jimage file format changed slightly, introducing
an extra level of nesting. These changes support that
new structure (b74).

The ANT targets in build.xml will still enable transformation of the packaging from org.aspectj.apache to org.apache for diffing with a new BCEL version, should one ever appear.