[doc] Add migration guide for PMD 7

docs/_data/sidebars/pmd_sidebar.yml

@@ -34,6 +34,9 @@ entries:
   - title: User Documentation
     output: web, pdf
     folderitems:
+    - title: Migration Guide for PMD 7
+      url: /pmd_userdocs_migrating_to_pmd7.html
+      output: web, pdf
     - title: Installation and basic CLI usage
       url: /pmd_userdocs_installation.html
       output: web, pdf

docs/pages/pmd/userdocs/migrating_to_pmd7.md

@@ -0,0 +1,98 @@
+---
+title: Migration Guide for PMD 7
+tags: [pmd, userdocs]
+summary: "Migrating to PMD 7 from PMD 6.x"
+permalink: pmd_userdocs_migrating_to_pmd7.html
+author: Andreas Dangel <andreas.dangel@pmd-code.org>
+---
+
+## In general
+
+Update to the latest PMD 6.x version and try to fix deprecation warnings
+
+Deprecations in PMD 6:
+* Properties:
+  StringProperty.named(...) -> PropertyFactory.stringProperty(...)
+  uiOrder is gone
+* addViolation(data, node, ...) -> asCtx(data).addViolation(node, ...)
+* deprecated cli params
+  -no-cache --> --no-cache
+  -failOnViolation --> --fail-on-violation
+  -reportfile --> --report-file
+  -language --> --use-version
+* deprecated XPath attributes
+WARNING: Use of deprecated attribute 'VariableDeclaratorId/@Image' by XPath rule 'VariableNaming' (in ruleset 'VariableNamingRule'), please use @Name instead
+
+
+
+## Use cases
+
+### I'm using only built-in rules
+
+check whether the ruleset/rules are still available,
+have the same properties, etc.
+
+### I'm using custom rules
+
+make sure to have good test coverage for your custom rules first.
+if XPath, need to migrate to XPath 2.0. if Java, some APIs/ASTs might have changed.
+
+### I've extended PMD with a custom language...
+
+### I've extended PMD with a custom feature...
+
+## Special topics
+
+### CLI Changes
+
+run.sh pmd -> pmd check
+
+Message: [main] ERROR net.sourceforge.pmd.cli.commands.internal.PmdCommand - No such file false
+--> comes from "--fail-on-violation false" -> "--no-fail-on-violation"
+
+### Custom distribution packages
+needs pmd-cli dependencies
+needs cyclonedx plugin
+additional config needed to include conf/simpelogger.properties
+
+### Migrate rulechain rules:
+
+* RuleChain API changes, see [core] Simplify the rulechain #2490
+* addRuleChainVisit() -> buildTargetSelector()
+
+### Rule tests
+
+Nice to have - not immediately required:
+Should replace junit4 with junit5
+But both would work.
+
+### Endcolumn
+
+CPD: End Columns of Tokens are exclusive on PMD 7,
+but inclusive on PMD 6.x. See 5b7ed58
+
+
+### XPath
+
+Differences between XPath 1.0 and 2.0 (focused on practicality, eg how to transition)
+
+This is already in place: [Writing XPath rules - Migrating from 1.0 to 2.0](pmd_userdocs_extending_writing_xpath_rules.html#migrating-from-10-to-20)
+That means: The section migrating from XPath 1.0 -> XPath 2.0 should be moved to the migration guide PMD6->7
+since only XPath 2.0 (actually XPath 3.1) will be supported with PMD 7.
+
+Custom function "pmd:matches" has been removed, use the built in function from XPath 2.0+.
+
+### AST Navigation in general
+
+Methods like Node::getFirstChildOfType... use replacement either, NodeStream or in that case Node::firstChild(...).
+
+### Java AST
+* See also [Java Clean Changes](https://github.com/pmd/pmd/wiki/Java_clean_changes)
+
+### Language versions
+
+For some languages, that previously hadn't any version, now there are versions, e.g. plsql.
+
+### Build Tools
+
+maven...