Remove unused import from UnmarshallingTransformer

Author: artembilan

spring-integration-xml/src/main/java/org/springframework/integration/xml/transformer/UnmarshallingTransformer.java

@@ -28,7 +28,6 @@
 import org.w3c.dom.Document;
 
 import org.springframework.integration.transformer.AbstractPayloadTransformer;
-import org.springframework.integration.transformer.Transformer;
 import org.springframework.integration.xml.source.DomSourceFactory;
 import org.springframework.integration.xml.source.SourceFactory;
 import org.springframework.messaging.MessagingException;