Fix NPE when description is empty

Author: jlamaille

src/main/java/com/qdesrame/openapi/diff/output/HtmlRender.java

@@ -12,6 +12,8 @@
 import io.swagger.v3.oas.models.parameters.Parameter;
 import io.swagger.v3.oas.models.responses.ApiResponse;
 import j2html.tags.ContainerTag;
+import org.apache.commons.lang3.StringUtils;
+
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -347,7 +349,7 @@ private ContainerTag li_changedParam(ChangedParameter changeParam) {
       return li_deprecatedParam(changeParam);
     }
     boolean changeRequired = changeParam.isChangeRequired();
-    boolean changeDescription = changeParam.getDescription().isDifferent();
+    boolean changeDescription = Optional.ofNullable(changeParam.getDescription()).map(ChangedMetadata::isDifferent).orElse(false);
     Parameter rightParam = changeParam.getNewParameter();
     Parameter leftParam = changeParam.getNewParameter();
     ContainerTag li = li().withText(changeParam.getName() + " in " + changeParam.getIn());