Describe the PR

Update many (104) Java rules to pmd 7. There are still 179 of them

• This introduces a few new xpath functions, which are documented.
• Use a common utility class to share logic between rules (JavaRuleUtil), or to store procedures that are not really rule-specific
• Some rule base classes have been removed. In particular, AbstractJunitRule is turned into JUnitRuleUtil TestFrameworksUtil
• Some rules have been converted to XPath (which is why they're shown as deleted).
• I tried not to change the definition of rules. I implemented [java] Remove special cases from rule EmptyCatchBlock #2893 though

Related issues

• Refs [java] Java-grammar progress document #2701
• Fixes [java] AccessorMethodGeneration: Name clash with another public field not properly handled #342, [java] AccessorMethodGeneration false positive with overloads #807, [java] CloneMethodMustImplementCloneable triggers for interfaces #1005, [java] Don't raise JUnitTestContainsTooManyAsserts on JUnit 5's assertAll #1212, [java] InefficientEmptyStringCheck false negative in anonymous class #1224, [java] JUnitTestsShouldIncludeAssert false positive with inherited @Rule field #1422, [java] JUnitAssertionsShouldIncludeMessage false positive with AssertJ #1565, [java] MissingOverride false-positive triggered by package-private method overwritten in another package by extending class.  #1969, [java] AccessorClassGeneration false-negative: subclass calls private constructor #1998, [java] JUnitTestsShouldIncludeAssert - false positives with lambdas and static methods #2147, [java] MethodNamingConventions - JUnit 5 method naming not support ParameterizedTest #2528, [java] AvoidDecimalLiteralsInBigDecimalConstructor can not detect the case new BigDecimal(Expression) #2532, [java] DontCallThreadRun can't detect the case that call run() in this.run() #2537, [java] DontCallThreadRun can't detect the case that call run() in foo.bar.run() #2538, [java] UseCollectionIsEmpty can not detect the case foo.bar().size() #2542, [java] UseNotifyAllInsteadOfNotify falsely detect a special case with argument: foo.notify(bar) #2577, [java] AvoidArrayLoops could also check for list copy through iterated List.add() #2587, [java] AssertJ SimplifyStartsWith false-positive #2712, [java] CompareObjectsWithEqualsRule: False positive with Enums #2716, [java] SwitchStmtsShouldHaveDefault false-positive with Java 14 switch non-fallthrough branches #2806, [java] CompareObjectsWithEquals - false negative with type res #2880, [java] JUnitAssertionsShouldIncludeMessage false positive with method call #2883

Ready?

• Added unit tests for fixed bug/feature
  • Unit tests for new XPath functions are missing (done in [java] New Java XPath functions #2917)
• Passing all unit tests
• Complete build ./mvnw clean verify passes (checked automatically by travis)
• Added (in-code) documentation (if needed)