Add more rules

[lyxell]

• These are all pretty nice https://rules.sonarsource.com/java/RSPEC-4034
• Consider rule for flipping conditional branches
  • !x ? a : b => x ? b : a and if (!x) a else b => if (x) b else a
• Consider rule for merging if-statements
  • Possible deep rewrite: https://sonarqube.ow2.org/project/issues?id=fr.inria.gforge.spoon%3Aspoon-core&issues=AXBwJ6KLd67NGAIs__yK&open=AXBwJ6KLd67NGAIs__yK
• Consider S1157 - Case insensitive string comparisons should be made without intermediate
  • https://sonarqube.ow2.org/project/issues?id=fr.inria.gforge.spoon%3Aspoon-core&issues=AWhzp-kEOQZh-5uoMgA6&open=AWhzp-kEOQZh-5uoMgA6
• Consider S4838 - An iteration on a Collection should be performed on the type handled by the Collection
• Consider S1168 - Empty arrays and collections should be returned instead of null
  • PMD: https://pmd.github.io/latest/pmd_rules_java_errorprone.html#returnemptyarrayratherthannull
• Consider S1141 - Try-catch blocks should not be nested
• Consider S3631 - Arrays.stream should be used for primitive arrays
  • https://rules.sonarsource.com/java/RSPEC-3631
• Consider rule for transforming for-loop into foreach
  • https://pmd.github.io/pmd-6.36.0/pmd_rules_java_bestpractices.html#forloopcanbeforeach
• Consider S3985 - Unused private classes should be removed
• Consider S2093 - Try-with-resources should be used
• Consider S3067 - getClass should not be used for synchronization
• Consider S1450 - Private fields only used as local variables in methods should become local variables
• Consider S1158 - Primitive wrappers should not be instantiated only for "toString" or "compareTo" calls
• Consider S2583 - Conditionally executed code should be reachable
• Consider S1643 - Strings should not be concatenated using '+' in a loop
  • https://sonarqube.ow2.org/project/issues?id=fr.inria.gforge.spoon%3Aspoon-core&issues=AW1cCBplbu-R5OS5-LCy&open=AW1cCBplbu-R5OS5-LCy
• Consider S2276 - wait(...) should be used instead of Thread.sleep(...) when a lock is held
• Consider S5194 - Use Java 12 switch expression
• Consider S3012 - Arrays should not be copied using loops
• Consider S4201 - Null checks should not be used with "instanceof"
• Consider S1862 - Related "if/else if" statements should not have the same condition
• UR: Uninitialized read of field in constructor (UR_UNINIT_READ)
• Dm: Method invokes inefficient new String(String) constructor (DM_STRING_CTOR)
• Dm: Method invokes inefficient new String() constructor (DM_STRING_VOID_CTOR)
  
• Dm: Method invokes toString() method on a String (DM_STRING_TOSTRING)
• Dm: Method invokes inefficient Boolean constructor; use Boolean.valueOf(…) instead
• Bx: Method invokes inefficient Number constructor; use static valueOf instead (DM_NUMBER_CTOR)
  
• Bx: Method invokes inefficient floating-point Number constructor; use static valueOf instead (DM_FP_NUMBER_CTOR)
• IIL: Method calls Pattern.compile in a loop (IIL_PATTERN_COMPILE_IN_LOOP)

[lyxell]

		return childFragments.stream()
				.filter(ElementSourceFragment.class::isInstance)
				.map(ElementSourceFragment.class::cast)
				.map(ElementSourceFragment::getRoleInParent)
				.map(role::equals)
				.findAny()
-				.orElse(false);
+				.isPresent();

[lyxell]

     private String getVariableName(String className) {
-       variableCount.computeIfAbsent(className, k -> 0);
-       int count = variableCount.get(className);
+       int count = variableCount.computeIfAbsent(className, k -> 0);