private static HashType getHashType(PemKeyType pemKeyType) {
    switch (pemKeyType.hash) {
      case SHA256:
        return HashType.SHA256;
      case SHA384:
        return HashType.SHA384;
      case SHA512:
        return HashType.SHA512;
      default:
        break;
    }
    throw new IllegalArgumentException("unsupported hash type: " + pemKeyType.hash.name());
  }
Reads a single PEM key from {@code reader}. Invalid or unparsable PEM would be ignored
java_src/src/main/java/com/google/crypto/tink/signature/SignaturePemKeysetReader.java