Sonar fixes

- a few complexities
- final method calls from ctor
- raw exception throwing
- useless overrides
- loss of stack trace

spring-integration-file/src/main/java/org/springframework/integration/file/remote/synchronizer/AbstractInboundFileSynchronizingMessageSource.java

@@ -283,7 +283,7 @@ public abstract class AbstractInboundFileSynchronizingMessageSource<F>
 		}
 
 		@Override
-		protected AbstractIntegrationMessageBuilder<File> doReceive() {
+		protected AbstractIntegrationMessageBuilder<File> doReceive() { // NOSONAR - not useless, increases visibility
 			return super.doReceive();
 		}