Do not run the asciidoc documentation generation on JDK 5 as Gradle fails to generate a proxy for the AsciidoctorTask.
Better check for JDK 5
Move the check for existence of the asciidoc doc folder in the block checking JDK version
GROOVY-6216: Upgrade to ASM 4.1
    * move version numbers to variables
    * upgrade ASM to 4.1
    * upgrade Lucene example to Lucene 4.3.1
    * make "examples" task pass compilation
    * make "examples" task triggered by the "check" task
Fix typo (warning -> warn)
GROOVY-6215: Incorrect type inference with flow typing and switch statements