Sonar fixes

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

spring-integration-ftp/src/main/java/org/springframework/integration/ftp/session/DefaultFtpsSessionFactory.java

@@ -130,7 +130,7 @@ public class DefaultFtpsSessionFactory extends AbstractFtpSessionFactory<FTPSCli
 				throw (RuntimeException) e;
 			}
 
-			throw new RuntimeException("Failed to create FTPS client.", e);
+			throw new IllegalStateException("Failed to create FTPS client.", e);
 		}
 	}