@NotNull
  private static List<PyRequirementVersionSpec> parseVersionSpecs(@Nullable String versionSpecs) {
    if (versionSpecs == null) return Collections.emptyList();

    return StreamSupport
      .stream(StringUtil.tokenize(versionSpecs, ",").spliterator(), false)
      .map(String::trim)
      .map(PyRequirementParser::parseVersionSpec)
      .filter(req -> req != null)
      .collect(Collectors.toList());
  }
@NotNull
  private static List<PyRequirementVersionSpec> parseVersionSpecs(@Nullable String versionSpecs)