Java 17 features (H-M) (#15520)

- add missing @override
- Java style array syntax
- remove redundant modifiers
- always move String constants to left side in comparisons
- simplify lambda expressions and return statements
- use replace instead of replaceAll w/o regex
- instanceof matching and multiline strings
- remove null check before instanceof

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

bundles/org.openhab.binding.mail/src/3rdparty/java/javax/activation/PatchedMailcapCommandMap.java

@@ -168,8 +168,8 @@ public class PatchedMailcapCommandMap extends CommandMap {
                 if (fieldName.startsWith("x-java-") && fieldName.length() > 7) {
                     String command = fieldName.substring(7);
                     value = value.trim();
-                    if (command.equals("fallback-entry")) {
-                        if (value.equals("true")) {
+                    if ("fallback-entry".equals(command)) {
+                        if ("true".equals(value)) {
                             fallback = true;
                         }
                     }

bundles/org.openhab.binding.mail/src/main/java/org/openhab/binding/mail/internal/POP3IMAPHandler.java

@@ -169,9 +169,9 @@ public class POP3IMAPHandler extends BaseThingHandler {
                                 }
                                 Object rawContent = message.getContent();
                                 String contentAsString;
-                                if (rawContent instanceof String) {
+                                if (rawContent instanceof String str) {
                                     logger.trace("Detected plain text message");
-                                    contentAsString = (String) rawContent;
+                                    contentAsString = str;
                                 } else if (rawContent instanceof MimeMessage mimeMessage) {
                                     logger.trace("Detected MIME message");
                                     try (ByteArrayOutputStream os = new ByteArrayOutputStream()) {

bundles/org.openhab.binding.mail/src/main/java/org/openhab/binding/mail/internal/SMTPHandler.java

@@ -115,8 +115,7 @@ public class SMTPHandler extends BaseThingHandler {
                 Field dataField = dataSource.getClass().getDeclaredField("data");
                 dataField.setAccessible(true);
                 Object data = dataField.get(dataSource);
-                if (data instanceof MimeMultipart) {
-                    MimeMultipart mimeMultipart = (MimeMultipart) data;
+                if (data instanceof MimeMultipart mimeMultipart) {
                     for (int i = 0; i < mimeMultipart.getCount(); i++) {
                         Part mimePart = mimeMultipart.getBodyPart(i);
                         mimePart.getDataHandler().setCommandMap(commandMap);

bundles/org.openhab.binding.mail/src/main/java/org/openhab/binding/mail/internal/action/SendMailActions.java

@@ -230,8 +230,8 @@ public class SendMailActions implements ThingActions {
 
     @Override
     public void setThingHandler(@Nullable ThingHandler handler) {
-        if (handler instanceof SMTPHandler) {
-            this.handler = (SMTPHandler) handler;
+        if (handler instanceof SMTPHandler smtpHandler) {
+            this.handler = smtpHandler;
         }
     }