GH-3132: Remove usage of super();

Fixes https://github.com/spring-projects/spring-integration/issues/3132

It turns out that Checkstyle EmptyBlock doesn't complain about
empty default ctor.
Plus a new check for `super();` call treats it as a violation

* Remove `super();` from all the no-arg ctors
* Code style clean up in the affected classes according
IDEA suggestions

* Fix new Sonar smells

spring-integration-syslog/src/main/java/org/springframework/integration/syslog/SyslogHeaders.java

@@ -21,14 +21,15 @@ import org.springframework.integration.transformer.SyslogToMapTransformer;
 /**
  * Headers in a {@code Map} generated by the @link {@link SyslogToMapTransformer} that
  * will be added to Spring Integration messages as headers, prefixed by {@link #PREFIX}.
+ *
  * @author Gary Russell
+ *
  * @since 3.0
  *
  */
 public final class SyslogHeaders {
 
 	private SyslogHeaders() {
-		super();
 	}
 
 	public static final String PREFIX = "syslog_";