code: static NormalVersion parseVersionCore(String versionCore) {
          VersionParser parser = new VersionParser(versionCore);
          return parser.parseVersionCore();
      }
docs: Parses the version core.
  
  @param versionCore the version core string to parse
  @return a valid normal version object
  @throws IllegalArgumentException if the input string is {@code NULL} or empty
  @throws ParseException when there is a grammar error
  @throws UnexpectedCharacterException when encounters an unexpected character type