[infrastructure] add external null-annotations (#8848)

Signed-off-by: Jan N. Klug <jan.n.klug@rub.de>

bundles/org.openhab.binding.telegram/src/main/java/org/openhab/binding/telegram/internal/TelegramHandler.java

@@ -408,7 +408,7 @@ public class TelegramHandler extends BaseThingHandler {
         return replyIdToCallbackId.get(new ReplyKey(chatId, replyId));
     }
 
-    public Integer removeMessageId(Long chatId, String replyId) {
+    public @Nullable Integer removeMessageId(Long chatId, String replyId) {
         return replyIdToMessageId.remove(new ReplyKey(chatId, replyId));
     }
 

bundles/org.openhab.binding.telegram/src/main/java/org/openhab/binding/telegram/internal/action/TelegramActions.java

@@ -255,6 +255,9 @@ public class TelegramActions implements ThingActions {
     public boolean sendTelegram(@ActionInput(name = "chatId") @Nullable Long chatId,
             @ActionInput(name = "message") @Nullable String message,
             @ActionInput(name = "args") @Nullable Object... args) {
+        if (message == null) {
+            return false;
+        }
         return sendTelegram(chatId, String.format(message, args));
     }
 
@@ -444,7 +447,14 @@ public class TelegramActions implements ThingActions {
 
     public static boolean sendTelegramAnswer(ThingActions actions, @Nullable String chatId, @Nullable String replyId,
             @Nullable String message) {
-        return ((TelegramActions) actions).sendTelegramAnswer(Long.valueOf(chatId), replyId, message);
+        if (actions instanceof TelegramActions) {
+            if (chatId == null) {
+                return false;
+            }
+            return ((TelegramActions) actions).sendTelegramAnswer(Long.valueOf(chatId), replyId, message);
+        } else {
+            throw new IllegalArgumentException("Actions is not an instance of TelegramActions");
+        }
     }
 
     @Override