fix: change way of adding errors for metadata dates

AoU-ResourceServerCommon/src/main/java/ch/unige/aou/service/metadata/MetadataValidatorService.java

@@ -284,7 +284,7 @@ public abstract class MetadataValidatorService implements MetadataValidator {
     int index = 0;
     for (MetadataDates date: dates) {
       if (!StringTool.isNullOrEmpty(date.getContent()) && !ValidationTool.isValidDate(date.getContent())) {
-        errors.addError(new FieldError(publication.getClass().getSimpleName(), FORM_STEP_DESCRIPTION_PREFIX + "dates[" + index + "].date",
+        errors.addError(new FieldError(publication.getClass().getSimpleName(), FORM_STEP_DESCRIPTION_PREFIX + "dates."+ index + ".date",
                 this.messageService.get(ERROR_INVALID_DATE)));
       }
       index++;