code: public String getDisplayVariant(Locale locale) {
          String variantCode = baseLocale.getVariant();
          if (variantCode.isEmpty()) {
              return "";
          }
  
          try {
              normalizeAndValidateVariant(variantCode);
          } catch (IllformedLocaleException ilfe) {
              return variantCode;
          }
  
          String result = ICU.getDisplayVariant(this, locale);
          if (result == null) { // TODO: do we need to do this, or does ICU do it for us?
              result = ICU.getDisplayVariant(this, Locale.getDefault());
          }
  
          // The "old style" locale constructors allow us to pass in variants that aren't
          // valid BCP-47 variant subtags. When that happens, toLanguageTag will not emit
          // them. Note that we know variantCode.length() > 0 due to the isEmpty check at
          // the beginning of this function.
          if (result.isEmpty()) {
              return variantCode;
          }
          return result;
      }
docs: Returns the full variant name in the specified {@code Locale} for the variant code
  of this {@code Locale}. If there is no matching variant name, the variant code is
  returned.
  
  @since 1.7