code: public static String importProperty(MutableExtension extension, String propertySuffix, String def)
      {
          return StringUtils.defaultString(importProperty(extension, propertySuffix), def);
      }
docs: Delete and return the value of the passed special property.
  
  @param extension the extension from which to extract custom property
  @param propertySuffix the property suffix
  @param def the default value
  @return the value or {@code def} if none was found
  @since 8.3M1