Remove the 4 unused WikiModel serializers from xwiki-rendering-wikimodel

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Hi devs,

Since this is about removing public APIs I need to send a vote.

While looking at org.xwiki.rendering.wikimodel.xwiki.* in xwiki-rendering-wikimodel, I noticed that the WikiModel serializers are dead code. They came in with the original WikiModel import (XRENDERING-173, 2011) and were never wired to anything: XWiki serializes through the Renderer/Listener implementations in xwiki-rendering-syntaxes (e.g. XWikiSyntaxRenderer), never through WikiModel’s own serializers.

So I propose to remove these 4 classes:

  • org.xwiki.rendering.wikimodel.IWikiSerializer (34 lines) — interface with no implementors and no callers
  • org.xwiki.rendering.wikimodel.jspwiki.JspWikiSerializer (463 lines) — its javadoc literally says “Not ready yet.”
  • org.xwiki.rendering.wikimodel.xwiki.xwiki10.XWikiSerializer (185 lines) — XWiki 1.0 syntax serializer
  • org.xwiki.rendering.wikimodel.xwiki.xwiki20.XWikiSerializer2 (666 lines) — XWiki 2.0 syntax serializer

That’s ~1350 lines. I checked xwiki-rendering, xwiki-commons, xwiki-platform and the xwiki-contrib repos I have locally, and there isn’t a single reference to any of them. The only mentions anywhere are the two @see javadoc tags with which XWikiSerializer and XWikiSerializer2 point at each other.

To be clear, the rest of org.xwiki.rendering.wikimodel.xwiki.* stays: xwiki20.XWikiParser, xwiki21.XWikiParser, xwiki20.XWikiReferenceParser, xwiki20.XWikiScannerUtil and xwiki20.XWikiWikiParameters are all very much alive — the XWiki 2.0/2.1 parsers in xwiki-rendering-syntaxes delegate to them, and the JavaCC scanners import them.

I don’t think these 4 are worth moving to xwiki-rendering-legacy-wikimodel: they’re standalone leaf classes (nothing extends or implements them inside the codebase), and if someone really does use one, the 18.6.0 jar can still be added manually. So I’d go with a Revapi ignore in the root pom.xml:

<item>
  <ignore>true</ignore>
  <code>java.class.removed</code>
  <old>interface org.xwiki.rendering.wikimodel.IWikiSerializer</old>
  <criticality>highlight</criticality>
  <justification>Unused WikiModel serializer API. XWiki serializes through the Renderer/Listener implementations
    in xwiki-rendering-syntaxes, never through WikiModel's serializers. This interface was imported with
    WikiModel in XRENDERING-173 and has never had an implementor nor a caller.</justification>
</item>
<item>
  <ignore>true</ignore>
  <code>java.class.removed</code>
  <old>class org.xwiki.rendering.wikimodel.jspwiki.JspWikiSerializer</old>
  <criticality>highlight</criticality>
  <justification>Unused WikiModel serializer, never completed (its javadoc says "Not ready yet.") and never
    called. JSPWiki rendering is handled by xwiki-rendering-syntax-jspwiki.</justification>
</item>
<item>
  <ignore>true</ignore>
  <code>java.class.removed</code>
  <old>class org.xwiki.rendering.wikimodel.xwiki.xwiki10.XWikiSerializer</old>
  <criticality>highlight</criticality>
  <justification>Unused WikiModel serializer for XWiki 1.0 syntax, imported with WikiModel in XRENDERING-173 and
    never called. XWiki syntax rendering is handled by the renderers in xwiki-rendering-syntaxes.</justification>
</item>
<item>
  <ignore>true</ignore>
  <code>java.class.removed</code>
  <old>class org.xwiki.rendering.wikimodel.xwiki.xwiki20.XWikiSerializer2</old>
  <criticality>highlight</criticality>
  <justification>Unused WikiModel serializer for XWiki 2.0 syntax, imported with WikiModel in XRENDERING-173 and
    never called. XWiki syntax rendering is handled by the renderers in xwiki-rendering-syntaxes.</justification>
</item>

WDYT?

Here’s my +1

Thanks