Update changelog and add new rule to 540.xml

pmd-core/src/main/resources/rulesets/releases/540.xml

@@ -12,6 +12,7 @@ This ruleset contains links to rules that are new in PMD v5.4.0
     <rule ref="rulesets/java/comments.xml/CommentDefaultAccessModifier"/>
     <rule ref="rulesets/java/design.xml/SingleMethodSingleton"/>
     <rule ref="rulesets/java/design.xml/SingletonClassReturningNewInstance"/>
+    <rule ref="rulesets/java/unnecessary.xml/UselessQualifiedThis"/>
 
     <rule ref="rulesets/pom/basic.xml/ProjectVersionAsDependencyVersion"/>
     <rule ref="rulesets/pom/basic.xml/InvalidDependencyTypes"/>

pmd-java/src/main/resources/rulesets/java/unnecessary.xml

@@ -278,7 +278,7 @@ public class Foo {
 
   <rule name="UselessQualifiedThis"
       language="java"
-      since="5.3.3"
+      since="5.4.0"
       message="Useless qualified this usage in the same class."
       class="net.sourceforge.pmd.lang.rule.XPathRule"
       externalInfoUrl="${pmd.website.baseurl}/rules/java/unnecessary.html#UselessQualifiedThis">

src/site/markdown/overview/changelog.md

@@ -36,6 +36,8 @@
     can be simplified with a boolean expression.
 *   Modified Rule: rulesets/java/junit.xml/UseAssertTrueInsteadOfAssertEquals: This rule also flags
     assertEquals, that use Boolean.TRUE/FALSE constants.
+*   New Rule: rulesets/java/unnecessary.xml/UselessQualifiedThis: Flags unnecessary qualified usages
+    of this, when `this` alone would be unique. E.g. use just `this` instead of `Foo.this`.
 
 
 **Pull Requests:**
@@ -47,6 +49,7 @@
 *   [#57](https://github.com/pmd/pmd/pull/57): Add default access modifier as comment rule
 *   [#58](https://github.com/pmd/pmd/pull/58): Add rule for unnecessary literal boolean in ternary operators
 *   [#59](https://github.com/pmd/pmd/pull/59): Add check to Boxed booleans in UseAssertTrueInsteadOfAssertEquals rule
+*   [#60](https://github.com/pmd/pmd/pull/60): Add UselessQualifiedThisRule
 
 **Bugfixes:**