Target //http-filter-example:envoy failed to build

I have tried to build http-filter-example following [README.](https://github.com/envoyproxy/envoy-filter-example/blob/master/http-filter-example/README.md) The build fails with the error below
```
ERROR: /source/http-filter-example/BUILD:37:1: C++ compilation of rule '//http-filter-example:http_filter_config' failed (Exit 1) gcc failed: error executing command /usr/bin/gcc -U_FORTIFY_SOURCE -fstack-protector -Wall -Wunused-but-set-parameter -Wno-free-nonheap-object -fno-omit-frame-pointer '-std=c++0x' -MD -MF ... (remaining 917 argument(s) skipped)

Use --sandbox_debug to see verbose messages from the sandbox
http-filter-example/http_filter_config.cc: In member function 'virtual Envoy::Http::FilterFactoryCb Envoy::Server::Configuration::HttpSampleDecoderFilterConfig::createFilterFactoryFromProto(const google::protobuf::Message&, const string&, Envoy::Server::Configuration::FactoryContext&)':
http-filter-example/http_filter_config.cc:31:85: error: no matching function for call to 'Envoy::MessageUtil::downcastAndValidate(const google::protobuf::Message&)'
Envoy::MessageUtil::downcastAndValidate(proto_config), context);
^
In file included from bazel-out/k8-fastbuild/bin/external/envoy/include/envoy/upstream/_virtual_includes/locality_lib/envoy/upstream/locality.h:5:0,
from bazel-out/k8-fastbuild/bin/external/envoy/include/envoy/upstream/_virtual_includes/upstream_interface/envoy/upstream/upstream.h:22,
from bazel-out/k8-fastbuild/bin/external/envoy/include/envoy/grpc/_virtual_includes/context_interface/envoy/grpc/context.h:6,
from bazel-out/k8-fastbuild/bin/external/envoy/include/envoy/server/_virtual_includes/filter_config_interface/envoy/server/filter_config.h:7,
from http-filter-example/http_filter.h:5,
from http-filter-example/http_filter_config.cc:3:
bazel-out/k8-fastbuild/bin/external/envoy/source/common/protobuf/_virtual_includes/utility_lib/common/protobuf/utility.h:275:3: note: candidate: template static const MessageType& Envoy::MessageUtil::downcastAndValidate(const google::protobuf::Message&, Envoy::ProtobufMessage::ValidationVisitor&)
downcastAndValidate(const Protobuf::Message& config,
^~~~~~~~~~~~~~~~~~~
bazel-out/k8-fastbuild/bin/external/envoy/source/common/protobuf/_virtual_includes/utility_lib/common/protobuf/utility.h:275:3: note: template argument deduction/substitution failed:
http-filter-example/http_filter_config.cc:31:85: note: candidate expects 2 arguments, 1 provided
Envoy::MessageUtil::downcastAndValidate(proto_config), context);
^
Target //http-filter-example:envoy failed to build
```