[LUCENE-7727] Replace EOL'ed pegdown by flexmark-java for Java 9 compatibility

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 6.5, 7.0
• Component/s: general/build
• Labels: Java9
• Lucene Fields: New
• Assignee: Uwe Schindler
• Reporter: Uwe Schindler
• Created: 01/Mar/17 23:14
• Updated: 28/Aug/22 15:11
• Resolved: 02/Mar/17 16:46

Description

The documentation tasks use a library called "pegdown" to convert Markdown to HTML. Unfortunately, the developer of pegdown EOLed it and points the users to a faster replacement: flexmark-java (https://github.com/vsch/flexmark-java).

This would not be important for us, if pegdown would work with Java 9, but it is also affected by the usual "setAccessible into private Java APIs" issue (see my talk at FOSDEM: https://fosdem.org/2017/schedule/event/jigsaw_challenges/).

The migration should not be too hard, its just a bit of Groovy Code rewriting and dependency changes.

This is the pegdown problem:

Caused by: java.lang.RuntimeException: Could not determine whether class 'org.pegdown.Parser$$parboiled' has already been loaded
        at org.parboiled.transform.AsmUtils.findLoadedClass(AsmUtils.java:213)
        at org.parboiled.transform.ParserTransformer.transformParser(ParserTransformer.java:35)
        at org.parboiled.Parboiled.createParser(Parboiled.java:54)
        ... 50 more
Caused by: java.lang.reflect.InaccessibleObjectException: Unable to make protected final java.lang.Class java.lang.ClassLoader.findLoadedClass(java.lang.String) accessible: module java.base does not "opens java.lang" to unnamed module @551b6736
        at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:335)
        at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:278)
        at java.base/java.lang.reflect.Method.checkCanSetAccessible(Method.java:196)
        at java.base/java.lang.reflect.Method.setAccessible(Method.java:190)
        at org.parboiled.transform.AsmUtils.findLoadedClass(AsmUtils.java:206)
        ... 52 more

Issue Links

• blocks: LUCENE-7725 it should be possible to run "ant precommit" with java9