@Override
             protected void addCompletions(@NotNull CompletionParameters parameters,
                                           @NotNull ProcessingContext context,
                                           @NotNull CompletionResultSet result) {
               XmlTag tag = PsiTreeUtil.getParentOfType(parameters.getPosition(), XmlTag.class, false);
               if (tag != null && !hasEnumerationReference(parameters, result)) {
                 final XmlTag simpleContent = XmlUtil.getSchemaSimpleContent(tag);
                 if (simpleContent != null) {
                   XmlUtil.processEnumerationValues(simpleContent, (element) -> {
                     String value = element.getAttributeValue(VALUE_ATTR_NAME);
                     assert value != null;
                     result.addElement(LookupElementBuilder.create(value));
                     return true;
                   });
                 }
               }
             }
@Override
             protected void addCompletions(@NotNull CompletionParameters parameters,
                                           @NotNull ProcessingContext context,
                                           @NotNull CompletionResultSet result)