Fix SAT warnings (#14202)

* Fix SAT warnings

- checkstyle.ModifierOrderCheck
- checkstyle.OneStatementPerLineCheck
- checkstyle.NeedBracesCheck
- PMD.UseStandardCharsets
- PMD.UseCollectionIsEmpty
- PMD.UnusedLocalVariable
- PMD.SimplifyBooleanReturns where reasonable, suppress where
readability is better without change
- PMD.SimplifyBooleanExpressions

* Include StandardCharsets

Signed-off-by: Holger Friedrich <mail@holger-friedrich.de>

bundles/org.openhab.binding.squeezebox/src/main/java/org/openhab/binding/squeezebox/internal/handler/SqueezeBoxServerHandler.java

@@ -939,7 +939,7 @@ public class SqueezeBoxServerHandler extends BaseBridgeHandler {
                     boolean hasitems = "1".equals(entry.value);
                     if (f != null) {
                         // Except for some favorites (e.g. Spotify) use hasitems:1 and type:playlist
-                        if (hasitems && isTypePlaylist == false) {
+                        if (hasitems && !isTypePlaylist) {
                             // Skip subfolders
                             favorites.remove(f);
                             f = null;