Code coverage reporting / coveralls broken since moving to Java 8

[mattnworb]

Looking at https://coveralls.io/github/spotify/folsom , the coverage graph shows all 0s since #84 was merged:

This is because cobertura fails to instrument classes at runtime with exceptions like this in the Travis build:

[cobertura] WARN  [main] net.sourceforge.cobertura.instrument.CoberturaInstrumenter - Unable to instrument file /home/travis/build/spotify/folsom/target/generated-classes/cobertura/com/spotify/folsom/BackoffFunction.class
java.lang.IllegalArgumentException
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)

which leads to the coveralls plugin seeing 0 lines of code in 0 files:

[INFO] Starting Coveralls job for travis-ci (322863796)
[INFO] Git commit f660fb8 in master
[INFO] Writing Coveralls data to /home/travis/build/spotify/folsom/target/coveralls.json...
[INFO] Processing coverage report from /home/travis/build/spotify/folsom/target/site/cobertura/coverage.xml
[INFO] Successfully wrote Coveralls data in 62ms
[INFO] Gathered code coverage metrics for 0 source files with 0 lines of code:
[INFO] - 0 relevant lines
[INFO] - 0 covered lines
[INFO] - 0 missed lines
[INFO] Submitting Coveralls data to API
[INFO] Successfully submitted Coveralls data in 861ms for Job #424.1
[INFO] https://coveralls.io/jobs/32392210

The root cause seems to be that cobertura does not support Java 8:

• INVOKESPECIAL/STATIC on interfaces require ASM 5 cobertura/cobertura#248
• Fix Java8 instrumentation exception due to use of ASM4 API version. cobertura/cobertura#299

The underlying problem in cobertura has been fixed but there has not been a release in almost 3 years. The cobertura project seems to be dead.