message: Fix the gzip filter to use ProtobufTypes::String.
diff: @@ -76,8 +76,8 @@ Compressor::ZlibCompressorImpl::CompressionStrategy GzipFilterConfig::compressio
  }
  }
  -StringUtil::CaseUnorderedSet
  -GzipFilterConfig::contentTypeSet(const Protobuf::RepeatedPtrField<std::string>& types) {
  +StringUtil::CaseUnorderedSet GzipFilterConfig::contentTypeSet(
  + const Protobuf::RepeatedPtrField<Envoy::ProtobufTypes::String>& types) {
  return types.empty() ? StringUtil::CaseUnorderedSet(defaultContentEncoding().begin(),
  defaultContentEncoding().end())
  : StringUtil::CaseUnorderedSet(types.cbegin(), types.cend());
  